OFFSET
1,2
COMMENTS
EXAMPLE
PROG
(PARI) T(n) = ([4, -1; 1, 0]^n)[2, 1]
b(n) = my(v=divisors(n)); prod(i=1, #v, T(v[i])^moebius(n/v[i]))
a(n) = if(isprime(n)&&!(12%n), b(n), b(n)/gcd(n, b(n)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Aug 06 2019
STATUS
approved