login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A102146 a(n) = sigma(10^n - 1), where sigma(n) is the sum of positive divisors of n. 1
13, 156, 1520, 15912, 148512, 2042880, 14508000, 162493344, 1534205464, 16203253248, 144451398000, 2063316971520, 14903272088640, 158269280832000, 1614847741624320, 17205180696931968, 144444514193267496 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ray Chandler, Table of n, a(n) for n = 1..322

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, A002283, A070528.

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 21 19:25 EDT 2019. Contains 325199 sequences. (Running on oeis4.)