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A055825
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a(n) = T(2n+1,n), array T as in A055818.
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8
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1, 5, 24, 122, 640, 3422, 18536, 101362, 558336, 3093302, 17218168, 96214890, 539415552, 3032659086, 17091411912, 96527966178, 546184965120, 3095613086822, 17571039730136, 99868193737306, 568303494617472
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OFFSET
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0,2
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COMMENTS
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Also main diagonal of array: A(i,1)=i, A(1,j)=j; A(i,j) = 2*A(i,j-1) - A(i-1,j). - Benoit Cloitre, Feb 26 2003
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LINKS
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MAPLE
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T:= proc(i, j) option remember;
if i=0 or j=0 then 1
else add(add(T(h, m), m=0..j), h=0..i-1)
fi; end:
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MATHEMATICA
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T[i_, j_]:= T[i, j]= If[i==0 || j==0, 1, Sum[T[h, m], {h, 0, i-1}, {m, 0, j}]]; Table[T[n+1, n], {n, 0, 25}] (* G. C. Greubel, Jan 22 2020 *)
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PROG
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(Sage)
@CachedFunction
def T(i, j):
if (i==0 or j==0): return 1
else: return sum(sum(T(h, m) for m in (0..j)) for h in (0..i-1))
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CROSSREFS
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Cf. A055818, A055819, A055820, A055821, A055822, A055823, A055824, A055826, A055827, A055828, A055829.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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