81610

Appears in sequences

• Numbers n such that n^2 + 1, n^2 + 3, n^2 + 7 and n^2 + 9 are all primes.at n=9A057015
• a(n) = Sum_{k=0..floor(n/2)} (k+1) * binomial(2*k,2*n-4*k).at n=19A382300