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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; internal format)
OFFSET

0,3

LINKS

S. Heubach and T. Mansour, Enumeration of 3-letter patterns in compositions

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

Adjacent sequences:  A134041 A134042 A134043 * A134045 A134046 A134047

KEYWORD

nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 03 2007

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Last modified February 17 09:06 EST 2012. Contains 205999 sequences.