A102146 a(n) = sigma(10^n - 1), where sigma(n) is the sum of positive divisors of n.

13, 156, 1520, 15912, 148512, 2042880, 14508000, 162493344, 1534205464, 16203253248, 144451398000, 2063316971520, 14903272088640, 158269280832000, 1614847741624320, 17205180696931968, 144444514193267496

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..352 (terms 1..322 from Ray Chandler)

C. Caldwell, Sigma function.

Formula

a(n) = A000203(A002283(n)). - Ray Chandler, Apr 22 2017

Mathematica

DivisorSigma[1, 10^Range[20]-1] (* Harvey P. Dale, Jan 05 2012 *)

Prog

(PARI) a(n) = sigma(10^n-1); \\ Michel Marcus, Apr 22 2017

Crossrefs

Cf. A000203, A001270, A002283, A003020, A005422, A046053, A046107, A046412, A046415, A046416, A046417, A046418, A046419, A046420, A057951, A059892, A061075, A070528, A070529, A081317, A081318, A085035, A095370, A095413, A095414, A095417, A095418, A102347, A102380, A112505, A147556, A295503, A366669.

Sequence in context: A077416 A192092 A297454 * A162768 A097827 A163084

Adjacent sequences: A102143 A102144 A102145 * A102147 A102148 A102149

Keyword

nonn

Author

Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Feb 14 2005

Status

approved