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A119307
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Number triangle T(n,k)=sum{j=0..n, C(j,k)C(j,n-k)}.
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2
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1, 1, 1, 1, 5, 1, 1, 11, 11, 1, 1, 19, 46, 19, 1, 1, 29, 127, 127, 29, 1, 1, 41, 281, 517, 281, 41, 1, 1, 55, 541, 1579, 1579, 541, 55, 1, 1, 71, 946, 4001, 6376, 4001, 946, 71, 1, 1, 89, 1541, 8889, 20626, 20626, 8889, 1541, 89, 1, 1, 109, 2377, 17907, 56904, 82994
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OFFSET
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0,5
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COMMENTS
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T(n,k)=T(n,n-k). Second column is A028387. Row sums are A014300. Central coefficients T(2n,n) are A112029.
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LINKS
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EXAMPLE
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Triangle begins
1,
1, 1,
1, 5, 1,
1, 11, 11, 1,
1, 19, 46, 19, 1,
1, 29, 127, 127, 29, 1,
1, 41, 281, 517, 281, 41, 1
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MATHEMATICA
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Flatten[Table[Sum[Binomial[j, k] Binomial[j, n-k], {j, 0, n}], {n, 0, 10}, {k, 0, n}]] (* Indranil Ghosh, Mar 03 2017 *)
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PROG
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(PARI)
tabl(nn)={for (n=0, nn, for(k=0, n, print1(sum(j=0, n, binomial(j, k)*binomial(j, n-k)), ", "); ); print(); ); };
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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