Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A052633
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A052633 A simple regular expression in a labeled universe. +0
1
0, 0, 2, 18, 96, 600, 4320, 35280, 322560, 3265920, 36288000, 439084800, 5748019200, 80951270400, 1220496076800, 19615115520000, 334764638208000, 6046686277632000, 115242726703104000, 2311256907767808000 (list; graph; listen)
OFFSET

0,3

LINKS

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 579

FORMULA

E.g.f.: -x^2*(-x+x^2-1)/(-1+x)^2

Recurrence: {a(1)=0, a(0)=0, a(2)=2, a(3)=18, (-n^2-2*n-1)*a(n)+a(n+1)*n, a(4)=96}

n*n!

MAPLE

spec := [S, {S=Prod(Z, Z, Sequence(Z), Union(Z, Sequence(Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

restart:printlevel := -1; a := [0]; T := x->LambertW(-x); f := series(((1+T(x)))/(1-T(x)), x, 24); for m from 1 to 19 do a := [op(a), op(2*m, f)*m! ] od; print(a); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 28 2009]

CROSSREFS

Essentially the same as A001563.

Sequence in context: A070171 A036800 A157052 this_sequence A052638 A127553 A055357

Adjacent sequences: A052630 A052631 A052632 this_sequence A052634 A052635 A052636

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

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 December 7 08:40 EST 2009. Contains 170430 sequences.


AT&T Labs Research