489408

Appears in sequences

• G.f.: x^2*(x+1)^2/(x^3+x^2-1)^2.at n=38A228364
• Numbers n such that n-19, n-1, n+1 and n+19 are consecutive primes.at n=27A262668
• a(n) = Sum(psi(k-1)*psi(n-k-1),k=0..n)+(1-(-1)^n)/2, where psi(k) = A000931(k+6).at n=36A285187