A353803 a(n) = Product_{p^e||n} sigma(sigma(p^e)) - sigma(sigma(n)), where n = Product_{p^e||n}, with each p^e the maximal power of prime p that divides n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 24, 0, 0, 0, 0, 0, 42, 21, 0, 0, 0, 0, 0, 0, 0, 141, 0, 0, 72, 36, 56, 0, 0, 0, 48, 54, 0, 168, 0, 0, 0, 45, 0, 0, 0, 0, 78, 21, 0, 0, 141, 0, 108, 54, 0, 192, 0, 0, 0, 0, 64, 381, 0, 0, 168, 317, 0, 0, 0, 0, 0, 0, 168, 192, 0, 0, 0, 72, 0, 336, 188, 0, 144, 126, 0, 126, 112

Offset: 1

Author

Antti Karttunen, May 08 2022

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A051027, A353802, A353804, A353805, A353806.

Cf. A336547 (positions of 0's), A336548 (positions of terms > 0).

Cf. also A353753.

Programs

PARI

A051027(n) = sigma(sigma(n));
A353803(n) = { my(f = factor(n)); (prod(k=1, #f~, A051027(f[k, 1]^f[k, 2])) - A051027(n)); };

Formula

a(n) = A353802(n) - A051027(n).