A388991 a(n) is the numerator of ratio A326128(n) / A326127(n), with a(6) = 0 by convention.

0, 0, 0, 3, 0, 0, 0, 6, 8, 0, 0, 9, 0, 0, 0, 15, 0, 16, 0, 15, 0, 0, 0, 3, 24, 0, 12, 1, 0, 0, 0, 30, 0, 0, 0, 35, 0, 0, 0, 3, 0, 0, 0, 33, 10, 0, 0, 45, 48, 48, 0, 13, 0, 4, 0, 21, 0, 0, 0, 15, 0, 0, 28, 63, 0, 0, 0, 51, 0, 0, 0, 70, 0, 0, 36, 19, 0, 0, 0, 75, 80, 0, 0, 9, 0, 0, 0, 33, 0, 40, 0, 69, 0, 0, 0, 3, 0, 96, 44, 99

Offset

1,4

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences related to sigma(n).

Formula

For n <> 6, a(n) = A326128(n) / A326129(n).

Prog

(PARI)
A326127(n) = (sigma(n)-core(n)-n);
A326128(n) = (n-core(n));
A388991(n) = if(6==n, 0, numerator(A326128(n)/A326127(n)));

Crossrefs

Cf. A000203, A007913, A326127, A326128, A326129, A388992 (denominators).

Sequence in context: A161837 A389072 A299163 * A326128 A369931 A160086

Adjacent sequences: A388988 A388989 A388990 * A388992 A388993 A388994

Keyword

nonn,frac

Author

Antti Karttunen, Sep 22 2025

Status

approved