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A212421
Central coefficients of triangle A096815.
2
1, 1, 3, 6, 17, 42, 118, 320, 861, 2442, 6658, 18686, 52100, 146832, 410990, 1161722, 3282403, 9283968, 26336598, 74712158, 212613094, 605118528, 1726261816, 4926677982, 14079210098, 40247549662, 115175011608, 329707161766, 944566633454, 2707713181042
OFFSET
0,3
FORMULA
a(n) = T(2n,n), where T(n,k) = A096815(n,k).
MATHEMATICA
T[n_, k_] := T[n, k] = If[n < k || k < 0, 0, If[k = 1 || k == n, 1, Sum[T[n-k, j]T[k, k-j], {j, 0, k}]]]
Table[T[2n, n], {n, 0, 50}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Emanuele Munarini, May 16 2012
STATUS
approved