

A026714


Triangular array T read by rows: T(n,0)=T(n,n)=1 for n >= 0; for n >= 2 and 1<=k<=n1, T(n,k)=T(n1,k1)+T(n2,k1)+T(n1,k) if k=[ (n1)/2 ] or k=[ n/2 ] or k=[ (n+2)/2 ], else T(n,k)=T(n1,k1)+T(n1,k).


10



1, 1, 1, 1, 3, 1, 1, 5, 5, 1, 1, 7, 13, 7, 1, 1, 8, 25, 25, 8, 1, 1, 9, 40, 63, 40, 9, 1, 1, 10, 49, 128, 128, 49, 10, 1, 1, 11, 59, 217, 319, 217, 59, 11, 1, 1, 12, 70, 276, 664, 664, 276, 70, 12, 1, 1, 13, 82, 346, 1157, 1647, 1157, 346, 82, 13
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OFFSET

1,5


LINKS

Table of n, a(n) for n=1..65.


FORMULA

T(n, k) = number of paths from (0, 0) to (nk, k) in the directed graph having vertices (i, j) and edges (i, j)to(i+1, j) and (i, j)to(i, j+1) for i, j >= 0 and edges (i, j)to(i+1, j+1) if ij<=2.


CROSSREFS

Sequence in context: A103450 A128254 A277930 * A008288 A238339 A302997
Adjacent sequences: A026711 A026712 A026713 * A026715 A026716 A026717


KEYWORD

nonn,tabl


AUTHOR

Clark Kimberling


STATUS

approved



