A051290 - OEIS

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A051290

Triangular array T read by rows: T(n,k)=P(2n+3,n,2k+3), 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, 4, 1, 12, 6, 3, 32, 24, 24, 4, 80, 80, 120, 40, 10, 192, 240, 480, 240, 120, 15, 448, 672, 1680, 1120, 840, 210, 35, 1024, 1792, 5376, 4480, 4480, 1680, 560, 56, 2304, 4608, 16128, 16128, 20160, 10080, 5040, 1008, 126

(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..44.

EXAMPLE

Triangle begins:

4, 1;

12, 6, 3;

32, 24, 24, 4,