OFFSET
1,9
MAPLE
with(NumberTheory): a := proc(n) local v, d; v := (4^n - 2)*(4^n - 1);
for d in Divisors(2*n) do if isprime(d+1) then v := v/(d+1) fi od;
v / Radical(v) end: seq(a(n), n = 1..85);
MATHEMATICA
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Jul 20 2021
STATUS
approved