a(n) = (15*n^4 + 22*n^3 + 45*n^2 + 14*n) / 24.

Terms

a(0) =0a(1) =4a(2) =26a(3) =94a(4) =251a(5) =555a(6) =1079a(7) =1911a(8) =3154a(9) =4926a(10) =7360a(11) =10604a(12) =14821a(13) =20189a(14) =26901a(15) =35165a(16) =45204a(17) =57256a(18) =71574a(19) =88426a(20) =108095a(21) =130879a(22) =157091a(23) =187059a(24) =221126a(25) =259650a(26) =303004a(27) =351576a(28) =405769a(29) =466001