113570domain: NAppears in sequencesNumbers k such that k*4^k-1 is prime.at n=18A086661Numbers k of the form p^2 + 1 (for prime p) where k^2 + 1 is also prime.at n=9A235053a(n) = n*(n + 1)*(n^2 + n + 22)/24.at n=40A318054