Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A026123
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A026123 a(n) = number of (s(0),s(1),...,s(n)) such that every s(i) is a nonnegative integer, s(0) = 1, s(n) = 2, |s(1) - s(0)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2. Also a(n) = T(n,n-1), where T is the array in A026120; a(n) = U(n,n+1), where U is the array in A026148. +0
4
1, 4, 10, 28, 76, 209, 575, 1589, 4405, 12253, 34189, 95679, 268503, 755457, 2130717, 6023235, 17063139, 48434514, 137741280, 392407134, 1119766942, 3200326627, 9160055809, 26254474379, 75348899051, 216515177336, 622887159274 (list; graph; listen)
OFFSET

2,2

FORMULA

G.f.: z^2(-1+(1-z)^2M^3), with M the g.f. of the Motzkin numbers (A001006).

CROSSREFS

First differences of A026134.

Sequence in context: A111308 A121302 A026150 this_sequence A091468 A103457 A083587

Adjacent sequences: A026120 A026121 A026122 this_sequence A026124 A026125 A026126

KEYWORD

nonn

AUTHOR

Clark Kimberling (ck6(AT)evansville.edu)

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified July 25 02:12 EDT 2008. Contains 142294 sequences.


AT&T Labs Research