A099608 Table of crystal ball sequences for A_n lattices read by antidiagonals.
1, 1, 1, 1, 3, 1, 1, 5, 7, 1, 1, 7, 19, 13, 1, 1, 9, 37, 55, 21, 1, 1, 11, 61, 147, 131, 31, 1, 1, 13, 91, 309, 471, 271, 43, 1, 1, 15, 127, 561, 1251, 1281, 505, 57, 1, 1, 17, 169, 923, 2751, 4251, 3067, 869, 73, 1, 1, 19, 217, 1415, 5321, 11253, 12559, 6637, 1405, 91, 1
Offset: 0
Programs
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PARI
T(n,k)=sum(j=0,min(n,k),binomial(n+j,j)*binomial(n,j)*binomial(k,j))
Formula
T(n, k)=hypergeom([n+1, -n, -k], [1, 1], 1).
Comments