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
KEYWORD
base,easy,nonn
AUTHOR
Labos Elemer, May 27 2002
STATUS
approved