a(n) = Sum(P(i)*P(j), 1<=i<j<=n), where P(k) is the k-th Pell number A000129(k).

A213785

a(n) = Sum(P(i)*P(j), 1<=i<j<=n), where P(k) is the k-th Pell number A000129(k).

Terms

    a(0) =0a(1) =0a(2) =2a(3) =17a(4) =113a(5) =693a(6) =4123a(7) =24234a(8) =141738a(9) =827298a(10) =4824716a(11) =28127435a(12) =163955435a(13) =955642695a(14) =5569991317a(15) =32464523892a(16) =189217679988

External references