Triangle where the g.f. for row n equals d^n/dx^n (1+x+x^2)^n / n! for n>=0, as read by rows.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =6a(6) =7a(7) =24a(8) =30a(9) =20a(10) =19a(11) =80a(12) =150a(13) =140a(14) =70a(15) =51a(16) =270a(17) =630a(18) =840a(19) =630a(20) =252a(21) =141a(22) =882a(23) =2520a(24) =4200a(25) =4410a(26) =2772a(27) =924a(28) =393a(29) =2856