a(n) = Sum_{k=0..n} binomial(5*n+1,5*k).

A345455

a(n) = Sum_{k=0..n} binomial(5*n+1,5*k).

Terms

    a(0) =1a(1) =7a(2) =474a(3) =12393a(4) =427351a(5) =13333932a(6) =430470899a(7) =13733091643a(8) =439924466026

External references