A059348 Third diagonal of array in A059347.

2, 2, 3, 4, 7, 10, 19, 28, 56, 84, 174, 264, 561, 858, 1859, 2860, 6292, 9724, 21658, 33592, 75582, 117572, 266798, 416024, 950912, 1485800, 3417340, 5348880, 12369285, 19389690, 45052515, 70715340, 165002460, 259289580, 607283490

Offset

2,1

Comments

Same as A104722 except for leading term (both have rational g.f.s). - R. J. Mathar and Franklin T. Adams-Watters, May 19 2008

Links

G. C. Greubel, Table of n, a(n) for n = 2..1000

F. R. Bernhart, Catalan, Motzkin and Riordan numbers, Discr. Math., 204 (1999), 73-112.

Formula

G.f.: 1 + ( (1 + x)*(1 - Sqrt[1 - 4*x^2])/(2*x^2))^2. - G. C. Greubel, Jan 08 2017

Mathematica

CoefficientList[Series[1 + ( (1 + x)*(1 - Sqrt[1 - 4*x^2])/(2*x^2))^2, {x, 0, 50}], x] (* G. C. Greubel, Jan 08 2017 *)

Prog

(PARI) Vec( 1 + ( (1 + x)*(1 - sqrt(1 - 4*x^2))/(2*x^2))^2 + O(x^25)) \\ G. C. Greubel, Jan 08 2017

Crossrefs

Cf. A059347, A104722.

Sequence in context: A143590 A336030 A245620 * A110871 A243856 A173433

Adjacent sequences: A059345 A059346 A059347 * A059349 A059350 A059351

Keyword

nonn

Author

N. J. A. Sloane, Jan 27 2001

Status

approved