A366634 - OEIS

A366634

Sum of the divisors of 7^n-1.

12, 124, 780, 7812, 33624, 354640, 1704240, 18929096, 97036800, 800520192, 3958188480, 56928231360, 193778020824, 1830926384640, 11181115146240, 115997032277280, 465294239722800, 5175558387507200, 22852200371636160, 287850454432579584, 1318081737957660000

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OFFSET

1,1

LINKS

Max Alekseyev, Table of n, a(n) for n = 1..388

FORMULA

a(n) = sigma(7^n-1) = A000203(A024075(n)).

EXAMPLE

a(5)=33624 because 7^5-1 has divisors {1, 2, 3, 6, 2801, 5602, 8403, 16806}.

MAPLE

a:=n->numtheory[sigma](7^n-1):

seq(a(n), n=1..100);