a(n) = (-n^5 + 15*n^4 - 65*n^3 + 125*n^2 - 34*n + 40)/40.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =14a(5) =28a(6) =49a(7) =71a(8) =79a(9) =46a(10) =-70a(11) =-329a(12) =-812a(13) =-1624a(14) =-2897a(15) =-4793a(16) =-7507a(17) =-11270a(18) =-16352a(19) =-23065a(20) =-31766a(21) =-42860a(22) =-56803a(23) =-74105a(24) =-95333a(25) =-121114a(26) =-152138a(27) =-189161a(28) =-233008a(29) =-284576