a(n) = Sum_{k=0..n} binomial(n,k)*w(k)*w(n-k) where w() = A000296().

A194689

a(n) = Sum_{k=0..n} binomial(n,k)*w(k)*w(n-k) where w() = A000296().

Terms

    a(0) =1a(1) =0a(2) =2a(3) =2a(4) =14a(5) =42a(6) =222a(7) =1066a(8) =6078a(9) =36490a(10) =238046a(11) =1653610a(12) =12214270a(13) =95361866a(14) =784071966a(15) =6764984362a(16) =61066919230a(17) =575200190986

External references