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A103968 Sigma((8^n - 1)/7), where sigma(n) is the sum of positive divisors of n. 1
1, 13, 74, 1092, 4864, 59200, 346112, 4756752, 19436692, 251916288, 1294876800, 20786304000, 79541043200, 1073030266880, 5303003316224, 81061789640832, 324992122224640, 4102172934143680, 20588576135708672, 376372958524932096 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..402

FORMULA

a(n) = A000203(A023001(n)). - Amiram Eldar, Feb 24 2020

MATHEMATICA

DivisorSigma[1, (8^Range[20]-1)/7] (* Harvey P. Dale, Aug 21 2011 *)

CROSSREFS

Cf. A000203, A023001.

Sequence in context: A094421 A301882 A302079 * A073544 A051361 A114070

Adjacent sequences:  A103965 A103966 A103967 * A103969 A103970 A103971

KEYWORD

nonn

AUTHOR

Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Mar 31 2005

STATUS

approved

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Last modified May 12 10:54 EDT 2021. Contains 343821 sequences. (Running on oeis4.)