a(n)=Sum{T(n,k)*T(n,k+2)}, 0<=k<=2n-2, T given by A027926.

Terms

a(0) =6a(1) =26a(2) =106a(3) =424a(4) =1684a(5) =6667a(6) =26352a(7) =104069a(8) =410806a(9) =1621325a(10) =6398688a(11) =25254823a(12) =99691822a(13) =393600358a(14) =1554333406a(15) =6139498384a(16) =24256359424a(17) =95857063972a(18) =378903471934