OFFSET
0,1
COMMENTS
a(n) is nearly 10^(3*n) because a(n) is almost (10^n+1)^3.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..18
FORMULA
a(n) = A007331(10^n + 1).
a(n) = Sum_{d|10^n+1, (10^n+1)/d == 1 mod 2} d^3.
EXAMPLE
a(0) = Sum_{d|2, 2/d == 1 mod 2} d^3 = 2^3 = 8.
a(1) = Sum_{d|11, 11/d == 1 mod 2} d^3 = 11^3 + 1^3 = 1332.
a(2) = Sum_{d|101, 101/d == 1 mod 2} d^3 = 101^3 + 1^3 = 1030302.
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 06 2017
STATUS
approved