A092344 a(0)=1; a(n) = sigma_2(n) + sigma_3(n).

1, 2, 14, 38, 94, 152, 302, 394, 670, 848, 1264, 1454, 2254, 2368, 3346, 3788, 5022, 5204, 7268, 7222, 9744, 10132, 12598, 12698, 17230, 16402, 20632, 21260, 26162, 25232, 33052, 30754, 38814, 38516, 45676, 44644, 57172, 52024, 63550, 63244, 75920, 70604, 89188

Offset: 0

Author

N. J. A. Sloane, Mar 20 2004

Keywords

• nonn
• easy

Links

• Amiram Eldar, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A001157, A001158.

Programs

Mathematica

Join[{1},Table[DivisorSigma[2,n]+DivisorSigma[3,n],{n,50}]] (* Harvey P. Dale, Feb 05 2020 *)

PARI

a(n) = if(n == 0, 1, my(f = factor(n)); sigma(f, 3) + sigma(f, 2)); \\ Amiram Eldar, Jan 02 2025

Formula

G.f.: 1 + Sum_{k>=1} k^2*(k + 1)*x^k/(1 - x^k). - Ilya Gutkovskiy, Mar 17 2017