A055873 a(0) = 1; a(n) = sum_{k=1 to d(n)} [a(n-k)] where d(n) is number of positive divisors of n.

1, 1, 2, 3, 6, 9, 20, 29, 64, 113, 226, 339, 791, 1130, 2486, 4746, 9492, 14238, 32883, 47121, 110966, 205208, 396178, 601386, 1417472, 2415036, 4830072, 9263966, 18924110, 28188076, 66036296, 94224372, 221466892, 409915636, 791643196

Offset

0,3

Links

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

Example

Since d(8) = 4, a(8) = a(7) +a(6) +a(5) +a(4) {4 terms}. So a(8) = 29 +20 +9 +6 =64.

Mathematica

Module[{lst={1}, n=1}, Do[AppendTo[lst, Total[Take[lst, -DivisorSigma[0, n]]]]; n++, {40}]; lst] (* Harvey P. Dale, May 01 2012 *)

Crossrefs

Sequence in context: A003243 A320160 A383447 * A246565 A320169 A379696

Adjacent sequences: A055870 A055871 A055872 * A055874 A055875 A055876

Keyword

easy,nonn

Author

Leroy Quet, Jul 16 2000

Status

approved