1-sequence of reduction of tetrahedral number sequence by x^2 -> x+1.

Terms

a(0) =0a(1) =4a(2) =14a(3) =54a(4) =159a(5) =439a(6) =1111a(7) =2671a(8) =6136a(9) =13616a(10) =29346a(11) =61742a(12) =127262a(13) =257742a(14) =514102a(15) =1011862a(16) =1968265a(17) =3788845a(18) =7225565a(19) =13664305a(20) =25645120a(21) =47799824a(22) =88535124a(23) =163043324a(24) =298669724a(25) =544451624a(26) =988021646a(27) =1785478726a(28) =3214039171