(P(p)-1)/2/p^2 where p runs through the odd primes different from 5 and P(k) is the k-th central pentanomial coefficient (A005191).

A087189

(P(p)-1)/2/p^2 where p runs through the odd primes different from 5 and P(k) is the k-th central pentanomial coefficient (A005191).

Terms

    a(0) =1a(1) =83a(2) =16907a(3) =279021a(4) =89444018a(5) =1695011087a(6) =658067703933

External references