A296070 Partial sums of A296069.

0, 2, 3, 8, 5, 12, 7, 16, 9, 20, 11, 24, 13, 28, 15, 32, 17, 36, 19, 40, 21, 44, 23, 48, 25, 52, 27, 56, 29, 60, 31, 64, 33, 68, 35, 72, 37, 76, 39, 80, 41, 84, 43, 88, 45, 92, 47, 96, 49, 100, 51, 104, 53, 108, 55, 112, 57, 116, 59, 120

Offset

1,2

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (0,2,0,-1).

Formula

From Colin Barker, Mar 19 2020: (Start)

G.f.: x^2*(2 + 3*x + 4*x^2 - x^3 - 2*x^4) / ((1 - x)^2*(1 + x)^2).

a(n) = 2*a(n-2) - a(n-4) for n>6.

a(n) = (3 + (-1)^n)*n / 2 for n>2.

(End)

Mathematica

Accumulate@ Nest[Append[#, Block[{k = 1, s = 1}, While[Nand[FreeQ[#, s k], And[IntegerQ@ Mean@ #, Total@ # != 0] &@ Append[#, s k]], If[s == 1, s = -1, k++; s = 1]]; s k]] &, {0}, 59] (* Michael De Vlieger, Dec 12 2017 *)

Prog

(PARI) concat(0, Vec(x^2*(2 + 3*x + 4*x^2 - x^3 - 2*x^4) / ((1 - x)^2*(1 + x)^2) + O(x^80))) \\ Colin Barker, Mar 19 2020

Crossrefs

Cf. A296069.

Sequence in context: A340393 A332222 A126139 * A060872 A162775 A363501

Adjacent sequences: A296067 A296068 A296069 * A296071 A296072 A296073

Keyword

nonn,easy

Author

Enrique Navarrete, Dec 04 2017

Status

approved