OFFSET
0,2
REFERENCES
A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..200
FORMULA
(n+1)*(5n-4)*a(n) - 2*(5n+1)(2n-1)*a(n-1) = 0. - R. J. Mathar, Jul 09 2012
G.f.: (2 - 3*x - 2*sqrt(1 - 4*x))/(x*sqrt(1 - 4*x)). - Ilya Gutkovskiy, Jun 13 2017
MATHEMATICA
Table[CatalanNumber[n](5n+1), {n, 0, 30}] (* Harvey P. Dale, Jul 27 2020 *)
PROG
(PARI) a(n) = (5*n+1)*binomial(2*n, n)/(n+1) \\ Michel Marcus, Jul 12 2013
(Magma) [Catalan(n)*(5*n+1):n in [0..27] ]; // Marius A. Burtea, Jan 05 2020
(Magma) R<x>:=PowerSeriesRing(Rationals(), 29); (Coefficients(R!((2-3*x-2*Sqrt(1-4*x))/(x*Sqrt(1-4*x))))); // Marius A. Burtea, Jan 05 2020
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Barry E. Williams, Dec 20 1999
EXTENSIONS
Terms a(21) and beyond from Andrew Howroyd, Jan 04 2020
STATUS
approved