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 A257556 Triangle, read by rows, T(n,k)= Sum_{i=0..(n-k)/2} C(2*k,i)*C(n-2*i-1,k-1). 0
 1, 1, 1, 3, 2, 1, 3, 7, 3, 1, 4, 12, 12, 4, 1, 4, 23, 28, 18, 5, 1, 4, 34, 66, 52, 25, 6, 1, 4, 49, 126, 143, 85, 33, 7, 1, 4, 64, 228, 328, 265, 128, 42, 8, 1, 4, 80, 372, 700, 701, 444, 182, 52, 9, 1, 4, 96, 573, 1352, 1705, 1320, 693, 248, 63 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS FORMULA G.f.: (x-1)/((x^5+2*x^3+x)*y+x-1). EXAMPLE 1; 1, 1; 3, 2, 1; 3, 7, 3, 1; 4, 12, 12, 4, 1; 4, 23, 28, 18, 5, 1; PROG (Maxima) T(n, k):=sum(binomial(2*k, i)*binomial(n-2*i-1, k-1), i, 0, (n-k)/2); (PARI) T(n, k)=sum(i=0, (n-k)\2, binomial(2*k, i)*binomial(n-2*i-1, k-1)) \\ Charles R Greathouse IV, Apr 30 2015 CROSSREFS Sequence in context: A147750 A089942 A097409 * A078268 A124782 A106611 Adjacent sequences:  A257553 A257554 A257555 * A257557 A257558 A257559 KEYWORD nonn,tabl AUTHOR Vladimir Kruchinin, Apr 29 2015 STATUS approved

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Last modified May 13 12:16 EDT 2021. Contains 343839 sequences. (Running on oeis4.)