|
Search: id:A052938
|
|
|
| A052938 |
|
A simple regular expression. |
|
+0
7
|
|
| 1, 3, 2, 4, 3, 5, 4, 6, 5, 7, 6, 8, 7, 9, 8, 10, 9, 11, 10, 12, 11, 13, 12, 14, 13, 15, 14, 16, 15, 17, 16, 18, 17, 19, 18, 20, 19, 21, 20, 22, 21, 23, 22, 24, 23, 25, 24, 26, 25, 27, 26, 28, 27, 29, 28, 30, 29, 31, 30, 32, 31, 33, 32, 34, 33, 35, 34, 36, 35, 37, 36, 38, 37, 39
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
LINKS
|
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 929
|
|
FORMULA
|
G.f.: -(-2*x+2*x^2-1)/(-1+x)/(-1+x^2)
Recurrence: {a(0)=1, a(2)=2, a(1)=3, a(n)+a(n+1)-n-4}
3/4*(-1)^(1-n)+1/2*n+7/4
A112034(n) = 3*2^a(n); a(n) = A109613(n+2) - A084964(n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 27 2005
a(n)=n-a(n-1)+2 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 21 2009]
|
|
EXAMPLE
|
For n=2, a(2)=2-1+2=3; n=3, a(3)=3-3+2=2; n=4, a(4)=4-2+2=4 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 21 2009]
|
|
MAPLE
|
spec := [S, {S=Prod(Union(Sequence(Z), Z, Z), Sequence(Prod(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
|
|
CROSSREFS
|
Cf. A028242 (same sequence with 1,0,2 prefix). [From Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jul 16 2009]
Sequence in context: A134559 A007456 A119707 this_sequence A140114 A025532 A133131
Adjacent sequences: A052935 A052936 A052937 this_sequence A052939 A052940 A052941
|
|
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
|
