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A102146
a(n) = sigma(10^n - 1), where sigma(n) is the sum of positive divisors of n.
9
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
KEYWORD
nonn
AUTHOR
Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Feb 14 2005
STATUS
approved