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 A026388 a(n) = number of integer strings s(0),...,s(n) counted by array T in A026386 that have s(n)=2; also a(n) = T(2n,n-1). 1
 1, 5, 24, 114, 541, 2573, 12275, 58747, 282003, 1357407, 6549906, 31675020, 153481299, 745011075, 3622111560, 17635418730, 85975792075, 419644943495, 2050493623760, 10029194506990, 49098707209695, 240568930012575 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Emeric Deutsch, Emanuele Munarini, Simone Rinaldi, Skew Dyck paths, area, and superdiagonal bargraphs, Journal of Statistical Planning and Inference, Vol. 140, Issue 6, June 2010, pp. 1550-1562. Table 1, y_n. László Németh, Tetrahedron trinomial coefficient transform, arXiv:1905.13475 [math.CO], 2019. FORMULA a(n) = hypergeom([3/2, 2, 1-n], [1, 3], -4). - Vladimir Reshetnikov, Apr 25 2016 Conjecture: -(n+1)*(2*n-1)*a(n) +(12*n^2-2*n+1)*a(n-1) -5*(2*n+1)*(n-2)*a(n-2)=0. - R. J. Mathar, Jun 21 2018 MATHEMATICA Table[HypergeometricPFQ[{3/2, 2, 1-n}, {1, 3}, -4], {n, 1, 20}] (* Vladimir Reshetnikov, Apr 25 2016 *) CROSSREFS Sequence in context: A141223 A289783 A140766 * A242509 A057969 A004254 Adjacent sequences:  A026385 A026386 A026387 * A026389 A026390 A026391 KEYWORD nonn AUTHOR STATUS approved

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Last modified October 23 17:32 EDT 2019. Contains 328373 sequences. (Running on oeis4.)