A051287 Triangular array T read by rows: T(n,k)=P(n,k,|n-2k|), 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, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 4, 4, 4, 1, 1, 4, 4, 4, 4, 1, 1, 6, 12, 8, 12, 6, 1, 1, 6, 12, 8, 8, 12, 6, 1, 1, 8, 24, 32, 16, 32, 24, 8, 1, 1, 8, 24, 32, 16, 16, 32, 24, 8, 1, 1, 10, 40, 80, 80, 32, 80, 80, 40, 10, 1, 1, 10, 40, 80, 80, 32, 32, 80

Offset

0,5

Comments

P(n,k,n) counts palindromes.

Links

Table of n, a(n) for n=0..73.

Sean A. Irvine, Java program (github)

Example

Rows: {1}; {1,1}; {1,2,1}; ...

Crossrefs

Sequence in context: A176653 A174842 A156074 * A278218 A216031 A263985

Adjacent sequences: A051284 A051285 A051286 * A051288 A051289 A051290

Keyword

nonn,tabl

Author

Clark Kimberling

Status

approved