A192374 Coefficient of x in the reduction of the polynomial p(n,x) defined at A162517 and below in Comments.

0, 2, 4, 28, 84, 406, 1448, 6200, 23688, 97034, 380716, 1533844, 6079452, 24339742, 96844496, 386805104, 1541301648, 6150529682, 24521644756, 97819530508, 390080615652, 1555871900710, 6204937972088, 24747735482792, 98698893741336

Offset

1,2

Comments

The polynomials p(n,x) is defined by ((x+d)^n-(x-d)^n)/(2d), where d=sqrt(x+4). A192374=2*A192375. For an introduction to reductions of polynomials by substitutions such as x^2->x+1, see A192232.

Links

Table of n, a(n) for n=1..25.

Formula

Empirical G.f.: 2*x^2/(9*x^4+6*x^3-10*x^2-2*x+1). [Colin Barker, Nov 23 2012]

Example

(See A192373.)

Mathematica

(See A192373.)

Crossrefs

Cf. A192232, A192373, A192375.

Sequence in context: A110881 A156449 A259375 * A274526 A264667 A356700

Adjacent sequences: A192371 A192372 A192373 * A192375 A192376 A192377

Keyword

nonn

Author

Clark Kimberling, Jun 29 2011

Status

approved