Triangle read by rows: T(n,k)=k*binomial(n-2k,3k+2) (n>=7, 1<=k<=(n-2)/5).

Terms

a(0) =1a(1) =6a(2) =21a(3) =56a(4) =126a(5) =252a(6) =2a(7) =462a(8) =18a(9) =792a(10) =90a(11) =1287a(12) =330a(13) =2002a(14) =990a(15) =3003a(16) =2574a(17) =3a(18) =4368a(19) =6006a(20) =36a(21) =6188a(22) =12870a(23) =234a(24) =8568a(25) =25740a(26) =1092a(27) =11628a(28) =48620a(29) =4095