Triangle, read by rows, where the n-th row lists the (2n+1) coefficients of (1 + x + 4x^2)^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =1a(5) =2a(6) =9a(7) =8a(8) =16a(9) =1a(10) =3a(11) =15a(12) =25a(13) =60a(14) =48a(15) =64a(16) =1a(17) =4a(18) =22a(19) =52a(20) =145a(21) =208a(22) =352a(23) =256a(24) =256a(25) =1a(26) =5a(27) =30a(28) =90a(29) =285