Triangular array read by rows: T(n,1) = T(n,n) = 1, T(n,k) = 4*T(n-1, k-1) + 2*T(n-1, k).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =1a(6) =1a(7) =16a(8) =26a(9) =1a(10) =1a(11) =36a(12) =116a(13) =106a(14) =1a(15) =1a(16) =76a(17) =376a(18) =676a(19) =426a(20) =1a(21) =1a(22) =156a(23) =1056a(24) =2856a(25) =3556a(26) =1706a(27) =1a(28) =1a(29) =316