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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

REFERENCES

E. Deutsch, E. Munarini, S. Rinaldi, Skew Dyck paths, area and superdiagonal bargraphs, J. Stat. Plan. Infer. 140 (6) (2010) 1550-1562 doi:10.1016/j.jspi.2009.12.013, Table 1, y_n.

LINKS

Table of n, a(n) for n=1..22.

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

Clark Kimberling

STATUS

approved

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Last modified October 19 20:05 EDT 2018. Contains 316378 sequences. (Running on oeis4.)