login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A268430 Number of North-East paths from (0,0) to (n,n) that have even number of times bounce off y = x to the right. 1
1, 2, 5, 16, 53, 184, 654, 2368, 8689, 32216, 120434, 453248, 1715266, 6521584, 24894364, 95353472, 366324729, 1411015064, 5447548682, 21074836864, 81682204614, 317110750672, 1232951721604, 4800353915264, 18712880651802, 73030245143792, 285311648317172 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

This sequence is related to paired pattern P_2 in Section 3.2 in Pan and Remmel's link.

LINKS

Table of n, a(n) for n=0..26.

Ran Pan, Jeffrey B. Remmel, Paired patterns in lattice paths, arXiv:1601.07988 [math.CO], 2016.

FORMULA

G.f.: (-1 + 3*f(x) - 2*x*(-2 + 5*f(x)+ 6*f(x)*x))/(2*(4*x - 1) (-1 + 4*x*(1 + x))), where f(x) = sqrt(1 - 4*x).

a(n) = binomial(2*n,n) - A268431(n).

CROSSREFS

Cf. A268407, A268429

Sequence in context: A001428 A055726 A101500 * A047006 A127498 A149958

Adjacent sequences:  A268427 A268428 A268429 * A268431 A268432 A268433

KEYWORD

nonn

AUTHOR

Ran Pan, Feb 04 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified September 26 06:54 EDT 2017. Contains 292502 sequences.