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A192369 Number of lattice paths from (0,0) to (n,n) using steps (0,1), (0,2), (1,0), (2,0), and (2,2). 7
1, 2, 15, 90, 617, 4248, 29945, 213404, 1535661, 11129314, 81123369, 594092166, 4367701295, 32216566492, 238301617605, 1766979857196, 13129849298327, 97746629874786, 728897653778335, 5443488765350770, 40706993579981847, 304779612155116444, 2284440756129389775, 17139937071103287600 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..23.

FORMULA

G.f. is a nested square root, see Maple program. - Mark van Hoeij, Apr 16 2013

MAPLE

p4 := (x-1)*(x^3+5*x^2+7*x-1);

ogf := sqrt(((2*x^2+4*x-3)/p4-2/sqrt(p4))/(4*x^2-8*x-5));

series(ogf, x=0, 30); # Mark van Hoeij, Apr 16 2013

PROG

(PARI) /* same as in A092566 but use */

steps=[[0, 1], [0, 2], [1, 0], [2, 0], [2, 2]];

/* Joerg Arndt, Jun 30 2011 */

CROSSREFS

Sequence in context: A275794 A037746 A037627 * A037753 A037641 A288952

Adjacent sequences:  A192366 A192367 A192368 * A192370 A192371 A192372

KEYWORD

nonn

AUTHOR

Eric Werley, Jun 29 2011

EXTENSIONS

Terms > 81123369 from Joerg Arndt, Jun 30 2011

STATUS

approved

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Last modified October 21 22:47 EDT 2019. Contains 328315 sequences. (Running on oeis4.)