A001307 Expansion of 1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20).

1, 2, 4, 6, 10, 14, 20, 26, 35, 44, 57, 70, 88, 106, 130, 154, 185, 216, 255, 294, 344, 394, 456, 518, 595, 672, 765, 858, 970, 1082, 1216, 1350, 1509, 1668, 1855, 2042, 2260, 2478, 2730, 2982, 3274, 3566, 3901, 4236, 4620, 5004, 5440, 5876, 6370, 6864

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 200

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

Formula

G.f.: 1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20).

Mathematica

CoefficientList[Series[1/(1-x)^2/(1-x^2)/(1-x^4)/(1-x^10)/(1-x^20), {x, 0, 50}], x] (* Vincenzo Librandi, Feb 24 2012 *)
LinearRecurrence[{2, 0, -2, 2, -2, 0, 2, -1, 0, 1, -2, 0, 2, -2, 2, 0, -2, 1, 0, 1, -2, 0, 2, -2, 2, 0, -2, 1, 0, -1, 2, 0, -2, 2, -2, 0, 2, -1}, {1, 2, 4, 6, 10, 14, 20, 26, 35, 44, 57, 70, 88, 106, 130, 154, 185, 216, 255, 294, 344, 394, 456, 518, 595, 672, 765, 858, 970, 1082, 1216, 1350, 1509, 1668, 1855, 2042, 2260, 2478}, 50] (* Harvey P. Dale, Aug 12 2021 *)

Crossrefs

Sequence in context: A115065 A333574 A008804 * A322010 A322003 A088932

Adjacent sequences: A001304 A001305 A001306 * A001308 A001309 A001310

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved