OFFSET
0,3
COMMENTS
a(A067201(n)) = 1, but these are not the only cases where a(k) = 1.
LINKS
Robert Israel, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: Sum_{k>=0} (Sum_{i in S(k)} x^i)/(1 - x^(k^2+2)) where S(k) = {i : 0 <= i < k^2 + 2, i^2 + 2 == 0 (mod k^2 + 2)}.
EXAMPLE
For n=2, n^2+2=6 is divisible by 0^2+2=2, 1^2+2=3 and 2^2+2=6 so a(2)=3.
MAPLE
a:= n -> nops(select(t -> issqr(t-2), numtheory:-divisors(n^2+2))):
seq(a(n), n=0..100);
PROG
(PARI) a(n) = my(m=n^2+2); sum(k=0, n, !(m % (k^2+2))); \\ Michel Marcus, Jun 12 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Aug 15 2014
STATUS
approved