A129369 Expansion of 1/sqrt(1-4x)-x/sqrt(1-4x^2).

1, 1, 6, 18, 70, 246, 924, 3412, 12870, 48550, 184756, 705180, 2704156, 10399676, 40116600, 155114088, 601080390, 2333593350, 9075135300, 35345215180, 137846528820, 538257689684, 2104098963720, 8233430022168, 32247603683100

Offset

0,3

Comments

Partial sums are A129368.

Links

Table of n, a(n) for n=0..24.

Formula

a(n)=C(2n,n)-C(n-1,(n-1)/2)(1-(-1)^n)/2;

Mathematica

CoefficientList[Series[1/Sqrt[1-4x]-x/Sqrt[1-4x^2], {x, 0, 30}], x] (* Harvey P. Dale, Feb 02 2012 *)

Crossrefs

Sequence in context: A200151 A000623 A304941 * A095853 A027266 A242278

Adjacent sequences: A129366 A129367 A129368 * A129370 A129371 A129372

Keyword

easy,nonn

Author

Paul Barry, Apr 11 2007

Status

approved