A071422 a(n) = a(n-1) + sum of decimal digits of sigma(n), the sum of divisors of n.

1, 4, 8, 15, 21, 24, 32, 38, 42, 51, 54, 64, 69, 75, 81, 85, 94, 106, 108, 114, 119, 128, 134, 140, 144, 150, 154, 165, 168, 177, 182, 191, 203, 212, 224, 234, 245, 251, 262, 271, 277, 292, 300, 312, 327, 336, 348, 355, 367, 379, 388, 405, 414, 417, 426, 429

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

s=0; Do[s=s+Apply[Plus, IntegerDigits[DivisorSigma[1, n]]]; Print[s], {n, 1, 128}]
nxt[{n_, a_}]:={n+1, a+Total[IntegerDigits[DivisorSigma[1, n+1]]]}; Transpose[ NestList[nxt, {1, 1}, 60]][[2]] (* Harvey P. Dale, Jan 25 2013 *)

Crossrefs

Cf. A037123, A000788, A051351.

Partial sums of A067342.

Sequence in context: A312751 A312752 A312753 * A368897 A212538 A113902

Adjacent sequences: A071419 A071420 A071421 * A071423 A071424 A071425

Keyword

base,easy,nonn

Author

Labos Elemer, May 27 2002

Status

approved