A090879 a(n) = Sum_{d|n} d*2^(n-d).
1, 4, 7, 20, 21, 94, 71, 328, 457, 1194, 1035, 7052, 4109, 17294, 33807, 83984, 65553, 389650, 262163, 1484820, 1949717, 4216854, 4194327, 29409304, 22020121, 67215386, 119799835, 350453788, 268435485, 1755807774, 1073741855
Offset: 1
Links
- Vaclav Kotesovec, Table of n, a(n) for n = 1..3000
Programs
-
Mathematica
f[n_] := Block[{d = Divisors[n]}, Apply[Plus, d*2^(n - d)]]; Table[ f[n], {n, 1, 32}] (* Robert G. Wilson v, Feb 16 2004 *)
Formula
G.f.: Sum_{m>0} m*x^m/(1-(2*x)^m).
Extensions
More terms from Robert G. Wilson v, Feb 16 2004