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A134044 Number of compositions of n with parts in N which avoid the pattern 221. 1
1, 1, 2, 4, 8, 15, 30, 58, 113, 220, 429, 835, 1627, 3169, 6172, 12023, 23419, 45616, 88853, 173073, 337118, 656656, 1279065, 2491423, 4852911, 9452731, 18412473, 35864686, 69858930, 136074521, 265052378, 516281541, 1005637564, 1958828336 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
S. Heubach and T. Mansour, Enumeration of 3-letter patterns in compositions, arXiv:math/0603285 [math.CO], 2006.
FORMULA
G.f.: 1/(1-Sum(x^j*Product(1-x^(2*i),i=j+1..inf),j=1..inf)).
CROSSREFS
Sequence in context: A077596 A091865 A065494 * A079967 A192655 A018088
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Oct 03 2007
STATUS
approved

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Last modified July 24 22:37 EDT 2024. Contains 374585 sequences. (Running on oeis4.)