A051289 - OEIS

A051289

Triangular array T read by rows: T(n,k)=P(2n+1,n,2k+1), where P(n,k,c)=number of vectors (x(1),x(2,),...,x(n)) of k 1's and n-k 0's such that x(i)=x(n+1-i) for exactly c values of i.

1, 2, 1, 4, 4, 2, 8, 12, 12, 3, 16, 32, 48, 24, 6, 32, 80, 160, 120, 60, 10, 64, 192, 480, 480, 360, 120, 20, 128, 448, 1344, 1680, 1680, 840, 280, 35, 256, 1024, 3584, 5376, 6720, 4480, 2240, 560, 70, 512, 2304, 9216, 16128, 24192

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

P(n,k,n) counts palindromes.

LINKS

Table of n, a(n) for n=0..49.

FORMULA

E.g.f.: exp(2*y)*(BesselI(0, 2*x*y)+BesselI(1, 2*x*y)). - Vladeta Jovovic, Dec 15 2004

EXAMPLE

Triangle begins:

2, 1;