|
Search: id:A052957
|
|
|
| A052957 |
|
A simple regular expression. |
|
+0
2
|
|
| 2, 2, 6, 8, 20, 32, 72, 128, 272, 512, 1056, 2048, 4160, 8192, 16512, 32768, 65792, 131072, 262656, 524288, 1049600, 2097152, 4196352, 8388608, 16781312, 33554432, 67117056, 134217728, 268451840, 536870912, 1073774592, 2147483648
(list; graph; listen)
|
|
|
OFFSET
|
0,1
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1028
|
|
FORMULA
|
G.f.: -2*(-1+x+x^2)/(-1+2*x^2)/(-1+2*x)
Recurrence: {a(1)=2, a(2)=6, a(0)=2, 4*a(n)-2*a(n+1)-2*a(n+2)+a(n+3)}
2^n+Sum(1/2*_alpha^(-n), _alpha=RootOf(-1+2*_Z^2))
|
|
MAPLE
|
spec := [S, {S=Union(Sequence(Prod(Union(Z, Z), Z)), Sequence(Union(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Sequence in context: A054153 A000673 A129383 this_sequence A157253 A074933 A003178
Adjacent sequences: A052954 A052955 A052956 this_sequence A052958 A052959 A052960
|
|
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 05 2000
|
|
|
Search completed in 0.002 seconds
|
