A092346 a(0)=1; a(n) = sigma_1(n) + sigma_2(n).

1, 2, 8, 14, 28, 32, 62, 58, 100, 104, 148, 134, 238, 184, 274, 284, 372, 308, 494, 382, 588, 532, 646, 554, 910, 682, 892, 860, 1106, 872, 1372, 994, 1428, 1268, 1504, 1348, 2002, 1408, 1870, 1756, 2300, 1724, 2596, 1894, 2646, 2444, 2722, 2258, 3534, 2508, 3348

Offset: 0

Author

N. J. A. Sloane, Mar 20 2004

Keywords

• nonn
• easy

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A000203, A001157.

Programs

Mathematica

Join[{1},DivisorSigma[1,#]+DivisorSigma[2,#]&/@Range[50]] (* Harvey P. Dale, Aug 12 2021 *)

PARI

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

Formula

G.f.: Sum_{n>=1} n*(n+1) * x^n/(1-x^n).