51269domain: NAppears in sequencesNumbers k such that binomial(5k, k) - 1 is prime.at n=20A125242a(1)=1, a(n) = a(n-1) + n^4 if n odd, a(n) = a(n-1) + n^5 if n is even.at n=8A140161Number of 2 X 2 matrices having all terms in {-n,...,0,...,n} and 0 <= determinant <= n.at n=14A211146