Question 22115: The Forward Transform Sums over All Positive Divisors

Original question and givens

Use positive integer n=15, exact integer arithmetic function f(k)=a*k+b with a=5, b=2. F(m) sums f(d) over every positive divisor d of m. Inversion uses mu(d)*F(m/d); complete prime multiplicities determine mu, with mu(1)=1. Do not replace d|m by d≤m or use only prime/proper divisors. Give (n, divisor_value_rows, F_n, certificate).

• G001 — Use positive integer n=15, exact integer arithmetic function f(k)=a*k+b with a=5, b=2. F(m) sums f(d) over every positive divisor d of m. Inversion uses mu(d)*F(m/d); complete prime multiplicities determine mu, with mu(1)=1. Do not replace d|m by d≤m or use only prime/proper divisors. Give (n, divisor_value_rows, F_n, certificate).

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

• mko-mobius-inversion-finite-divisors

Step-by-step derivation

source operation=mobinv-forward-divisor-transform;original snapshot and mathematics retained

explicit ordered source output fields=[n, divisor_value_rows, F_n, certificate]

Mobius inversion ORIGINAL forward:actual positive input=15;check complete integer range1..15

ALL positive divisors INCREASING=[1, 3, 5, 15];not only primes/proper divisors or all integers<=n

Mobius inversion ORIGINAL forward f(1) ORIGINAL a times divisor := mul(5, 1)

Mobius inversion ORIGINAL forward f(1) ORIGINAL a times divisor = 5

Mobius inversion ORIGINAL forward f(1) plus ORIGINAL b := sum(5, 2)

Mobius inversion ORIGINAL forward f(1) plus ORIGINAL b = 7

Mobius inversion ORIGINAL forward f(3) ORIGINAL a times divisor := mul(5, 3)

Mobius inversion ORIGINAL forward f(3) ORIGINAL a times divisor = 15

Mobius inversion ORIGINAL forward f(3) plus ORIGINAL b := sum(15, 2)

Mobius inversion ORIGINAL forward f(3) plus ORIGINAL b = 17

Mobius inversion ORIGINAL forward f(5) ORIGINAL a times divisor := mul(5, 5)

Mobius inversion ORIGINAL forward f(5) ORIGINAL a times divisor = 25

Mobius inversion ORIGINAL forward f(5) plus ORIGINAL b := sum(25, 2)

Mobius inversion ORIGINAL forward f(5) plus ORIGINAL b = 27

Mobius inversion ORIGINAL forward f(15) ORIGINAL a times divisor := mul(5, 15)

Mobius inversion ORIGINAL forward f(15) ORIGINAL a times divisor = 75

Mobius inversion ORIGINAL forward f(15) plus ORIGINAL b := sum(75, 2)

Mobius inversion ORIGINAL forward f(15) plus ORIGINAL b = 77

Mobius inversion ORIGINAL forward full forward divisor sum := sum(7, 17, 27, 77)

Mobius inversion ORIGINAL forward full forward divisor sum = 128

Reverse checks

• S011 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward full forward divisor sum with exact rational arithmetic, not rounded decimals.
• S010 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(15) plus ORIGINAL b with exact rational arithmetic, not rounded decimals.
• S009 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(15) ORIGINAL a times divisor with exact rational arithmetic, not rounded decimals.
• S008 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(5) plus ORIGINAL b with exact rational arithmetic, not rounded decimals.
• S007 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(5) ORIGINAL a times divisor with exact rational arithmetic, not rounded decimals.
• S006 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(3) plus ORIGINAL b with exact rational arithmetic, not rounded decimals.
• S005 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(3) ORIGINAL a times divisor with exact rational arithmetic, not rounded decimals.
• S004 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(1) plus ORIGINAL b with exact rational arithmetic, not rounded decimals.
• S003 · premise_and_result_audit — Recompute Mobius inversion ORIGINAL forward f(1) ORIGINAL a times divisor with exact rational arithmetic, not rounded decimals.
• S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
• S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(15, [[1, 7], [3, 17], [5, 27], [15, 77]], 128, sum_over_all_positive_divisors)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.