A140155 a(1)=1, a(n)=a(n-1)+n^3 if n odd, a(n)=a(n-1)+ n^4 if n is even.

1, 17, 44, 300, 425, 1721, 2064, 6160, 6889, 16889, 18220, 38956, 41153, 79569, 82944, 148480, 153393, 258369, 265228, 425228, 434489, 668745, 680912, 1012688, 1028313, 1485289, 1504972, 2119628, 2144017, 2954017, 2983808, 4032384

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

G.f.: -x*(x^2+1)*(x^6-16*x^5+21*x^4-160*x^3-21*x^2-16*x-1)/((1+x)^5*(x-1)^6). [From R. J. Mathar, Feb 22 2009]

Mathematica

a = {}; r = 3; s = 4; Do[k = 0; Do[k = k + (Sin[Pi m/2]^2) m^r + (Cos[Pi m/2]^2) m^s, {m, 1, n}]; AppendTo[a, k], {n, 1, 100}]; a (*Artur Jasinski*)
nxt[{n_, a_}]:={n+1, If[EvenQ[n], a+(n+1)^3, a+(n+1)^4]}; NestList[nxt, {1, 1}, 40][[;; , 2]] (* Harvey P. Dale, Oct 22 2023 *)

Crossrefs

Cf. A000027, A000217, A000330, A000537, A000538, A000539, A136047, A140113.

Sequence in context: A093191 A033703 A227721 * A221752 A032698 A120099

Adjacent sequences: A140152 A140153 A140154 * A140156 A140157 A140158

Keyword

nonn

Author

Artur Jasinski, May 12 2008

Status

approved