Triangle of binomial coefficients binomial(3*n-k,3*n-3*k).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =10a(5) =1a(6) =1a(7) =28a(8) =35a(9) =1a(10) =1a(11) =55a(12) =210a(13) =84a(14) =1a(15) =1a(16) =91a(17) =715a(18) =924a(19) =165a(20) =1a(21) =1a(22) =136a(23) =1820a(24) =5005a(25) =3003a(26) =286a(27) =1a(28) =1a(29) =190