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Search: id:A018218
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| A018218 |
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Sum(C(j)*(n-j)*4^(n-j-1),j=0..n-1), C = Catalan numbers. |
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6
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| 0, 1, 9, 58, 325, 1686, 8330, 39796, 185517, 848830, 3827230, 17053356, 75249954, 329353948, 1431575220, 6185613032, 26589395581, 113780713806, 484945025942, 2059546425340, 8719018250838, 36805967321684
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OFFSET
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0,3
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FORMULA
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a(n)=(n+1)(4^n-binomial(2*n+1, n))/2; G.f.: x*c(x)/(1-4*x)^2, where c(x) = g.f. for Catalan numbers A000108; also convolution of A000346(n-1), n >= 0, where A000346(-1)=0, with A000302 (powers of 4) - from Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de).
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CROSSREFS
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Sequence in context: A044528 A027174 A099624 this_sequence A026750 A009034 A026377
Adjacent sequences: A018215 A018216 A018217 this_sequence A018219 A018220 A018221
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Peter Winkler (pw(AT)bell-labs.com)
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