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A026714 Triangular array T read by rows: T(n,0)=T(n,n)=1 for n >= 0; for n >= 2 and 1<=k<=n-1, T(n,k)=T(n-1,k-1)+T(n-2,k-1)+T(n-1,k) if k=[ (n-1)/2 ] or k=[ n/2 ] or k=[ (n+2)/2 ], else T(n,k)=T(n-1,k-1)+T(n-1,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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

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

FORMULA

T(n, k) = number of paths from (0, 0) to (n-k, 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 |i-j|<=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

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Last modified January 17 17:23 EST 2019. Contains 319250 sequences. (Running on oeis4.)