|
Search: id:A052946
|
|
|
| A052946 |
|
A simple regular expression. |
|
+0
1
|
|
| 1, 1, 4, 10, 29, 80, 224, 624, 1741, 4855, 13541, 37765, 105326, 293751, 819264, 2284905, 6372539, 17772840, 49567974, 138243749, 385558106, 1075311210, 2999014106, 8364169855, 23327445251, 65059618751, 181449530649
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1005
|
|
FORMULA
|
G.f.: -(-1+x)^2/(-1+3*x-2*x^3+x^4)
Recurrence: {a(1)=1, a(0)=1, a(2)=4, a(n)-2*a(n+1)+3*a(n+3)-a(n+4), a(3)=10}
Sum(1/643*(79+128*_alpha-133*_alpha^2+40*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(-1+3*_Z-2*_Z^3+_Z^4))
|
|
MAPLE
|
spec := [S, {S=Sequence(Prod(Union(Prod(Sequence(Z), Sequence(Z)), Z), Z))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A111236 A164361 A006907 this_sequence A026152 A025179 A116388
Adjacent sequences: A052943 A052944 A052945 this_sequence A052947 A052948 A052949
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
|
|
EXTENSIONS
|
More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 06 2000
|
|
|
Search completed in 0.002 seconds
|
