Denominator of c(n) = (n^2+n+2)/((n+1)*(n+2)*(n+3)).

Terms

a(0) =3a(1) =6a(2) =15a(3) =60a(4) =105a(5) =21a(6) =126a(7) =360a(8) =495a(9) =330a(10) =429a(11) =1092a(12) =1365a(13) =420a(14) =1020a(15) =2448a(16) =2907a(17) =1710a(18) =1995a(19) =4620a(20) =5313a(21) =759a(22) =3450a(23) =7800a(24) =8775a(25) =4914a(26) =5481a(27) =12180a(28) =13485a(29) =3720