A086293 Sum of divisors of 7-smooth numbers.

1, 3, 4, 7, 6, 12, 8, 15, 13, 18, 28, 24, 24, 31, 39, 42, 32, 60, 31, 40, 56, 72, 63, 48, 91, 90, 96, 78, 124, 57, 93, 120, 120, 168, 104, 127, 144, 195, 124, 186, 121, 224, 234, 252, 171, 217, 192, 280, 248, 360, 156, 312, 255, 240, 336, 403, 228, 372, 378

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000203(A002473(n)).

Mathematica

DivisorSigma[1, Select[Range[500], Max[Transpose[FactorInteger[#]][[1]]] <= 7 &]] (* Amiram Eldar, Jan 06 2020 after G. C. Greubel at A086288 *)

Crossrefs

Cf. A000203, A002473, A086292.

Sequence in context: A003979 A084250 A090128 * A337708 A348944 A369761

Adjacent sequences: A086290 A086291 A086292 * A086294 A086295 A086296

Keyword

nonn

Author

Reinhard Zumkeller, Jul 15 2003

Status

approved