A103968 - OEIS

%I #8 Feb 24 2020 08:08:05

%S 1,13,74,1092,4864,59200,346112,4756752,19436692,251916288,1294876800,

%T 20786304000,79541043200,1073030266880,5303003316224,81061789640832,

%U 324992122224640,4102172934143680,20588576135708672,376372958524932096

%N Sigma((8^n - 1)/7), where sigma(n) is the sum of positive divisors of n.

%H Amiram Eldar, <a href="/A103968/b103968.txt">Table of n, a(n) for n = 1..402</a>

%F a(n) = A000203(A023001(n)). - _Amiram Eldar_, Feb 24 2020

%t DivisorSigma[1,(8^Range[20]-1)/7] (* _Harvey P. Dale_, Aug 21 2011 *)

%Y Cf. A000203, A023001.

%K nonn

%O 1,2

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