Triangle, read by rows, where T(n,k) = n!/(k!*(n-4*k)!*4^k) for n>=4*k>=0.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =6a(6) =1a(7) =30a(8) =1a(9) =90a(10) =1a(11) =210a(12) =1a(13) =420a(14) =1260a(15) =1a(16) =756a(17) =11340a(18) =1a(19) =1260a(20) =56700a(21) =1a(22) =1980a(23) =207900a(24) =1a(25) =2970a(26) =623700a(27) =1247400a(28) =1a(29) =4290