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Search: id:A013699
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| A013699 |
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Degree of variety K_{2,n}^2. |
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+0
5
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| 1, 32, 610, 9842, 147798, 2145600, 30664890, 435668420, 6186432967, 88066807556, 1258885297696, 18084694597452, 261164661944060, 3791317346771584, 55316720239735242, 810944384733610356
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Number of Catalan paths (nonnegative, starting and ending at 0, step +/-1) of 4n+4 steps with all values less than or equal to n+1 (see A080934).
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LINKS
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M. S. Ravi et al., Dynamic pole assignment and Schubert calculus, SIAM J. Control Optimization, 34 (1996), 813-832, esp. p. 825.
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PROGRAM
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(PARI) K(n, q=2)=(2*n+n*q+2*q)!*sum(j=0, q, ((q-2*j)*(n+2)+1)/(n+j*(n+2))!/(n+1+(q-j)*(n+2))!)
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CROSSREFS
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Cf. A013698 (q=1), A013700 (q=3), A013701 (q=4), A013702 (q=5).
Sequence in context: A022756 A088914 A036903 this_sequence A004337 A028204 A028190
Adjacent sequences: A013696 A013697 A013698 this_sequence A013700 A013701 A013702
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KEYWORD
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nonn,easy
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AUTHOR
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Joachim.Rosenthal(AT)nd.edu (Joachim Rosenthal)
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