This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A268401 Number of North-East lattice paths from (0,0) to (n,n) that bounce off the diagonal y = x to the right exactly three times. 1
 1, 6, 31, 146, 655, 2850, 12148, 51028, 212039, 873870, 3578404, 14578576, 59149381, 239177006, 964439355, 3879856458, 15577609711, 62439489346, 249917575553, 999080441830, 3989726087031, 15917901326330, 63457122234055, 252796365476922, 1006456231070795, 4004838954237250, 15928299669867291 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,2 COMMENTS This sequence is related to paired pattern P_2 in Pan and Remmel's link. By symmetry, it is also the umber of North-East lattice paths from (0,0) to (n,n) that bounce off the diagonal y = x to the left exactly three times. LINKS Ran Pan and Jeffrey B. Remmel, Paired patterns in lattice paths, arXiv:1601.07988 [math.CO], 2016. FORMULA G.f.: -((-1 + f(x))^4*x^2*(-1 + f(x) + 2*x))/(2*(1 - f(x) + (-5 + f(x))*x)^4), where f(x) = sqrt(1 - 4*x). CROSSREFS Cf. A268400. Sequence in context: A094951 A099621 A291002 * A240879 A056015 A128740 Adjacent sequences:  A268398 A268399 A268400 * A268402 A268403 A268404 KEYWORD nonn AUTHOR Ran Pan, Feb 03 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.

Last modified September 21 17:52 EDT 2018. Contains 315260 sequences. (Running on oeis4.)