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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128805 Number of valley-avoiding compositions with parts in N. 0
1, 1, 2, 4, 8, 15, 28, 52, 96, 177, 326, 600, 1104, 2032, 3740, 6884, 12672, 23327, 42942, 79052, 145528, 267905, 493192, 907928, 1671424, 3076959, 5664436, 10427772, 19196688, 35339553, 65057260, 119765152, 220477952, 405882064 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

LINKS

Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets

S. Heubach and T. Mansour, Enumeration of 3-letter patterns in combinations

FORMULA

The Heubach/Mansour paper has a complicated g.f.

CROSSREFS

Sequence in context: A008936 A073769 A008937 * A141018 A049864 A118870

Adjacent sequences:  A128802 A128803 A128804 * A128806 A128807 A128808

KEYWORD

nonn

AUTHOR

Ralf Stephan, May 08 2007

EXTENSIONS

More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 04 2007

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

Content is available under The OEIS End-User License Agreement .

Last modified February 16 07:39 EST 2012. Contains 205881 sequences.