A388281 a(n) = A276086(n)*A276086(sigma(n)-n) - A276086(sigma(n)), where A276086 is the primorial base exp-function, and sigma is the sum of divisors function.

0, 0, 3, 44, 31, 0, 5, 0, 220, 550, 155, 0, 25, 2750, 3875, 33736, 775, 93540, 125, 421700, 67479, 84340, 3875, 21826, 6236, 421700, 187185, 31627500, 22493, 0, 7, 0, 5425, 19250, 5425, 305564, 35, 118076, 81375, 826532, 1085, 763910, 175, 134750, 37975, 2951900, 5425, 9625266, 0, 916692, 3936275, 12397980, 27125

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..11550

Index entries for sequences related to primorial base.

Index entries for sequences related to sigma(n).

Formula

a(n) = A388282(n) - A388031(n) = A276086(n)*A379493(n) - A388031(n).

Prog

(PARI)
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A388281(n) = ((A276086(n)*A276086(sigma(n)-n)) - A276086(sigma(n)));

Crossrefs

Cf. A000203, A001065, A276086, A379493, A388031, A388280 (positions of 0's), A388282.

Sequence in context: A346200 A326970 A392068 * A076361 A130408 A349646

Adjacent sequences: A388278 A388279 A388280 * A388282 A388283 A388284

Keyword

nonn,look

Author

Antti Karttunen, Sep 16 2025

Status

approved