OFFSET
0,1
COMMENTS
a(n) is even because 10^n + 1 is not a square number.
LINKS
Max Alekseyev, Table of n, a(n) for n = 0..331
MATHEMATICA
a[0] = 2; a[n_] := DivisorSigma[0, 10^n + 1]; Array[a, 60, 0] (* Amiram Eldar, Jun 01 2021 *)
PROG
(PARI) a(n) = numdiv(10^n+1);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 01 2021
STATUS
approved