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A104858
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Partial sums of the little Schroeder numbers (A001003).
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0
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1, 2, 5, 16, 61, 258, 1161, 5440, 26233, 129282, 648141, 3294864, 16943733, 87983106, 460676625, 2429478144, 12893056497, 68802069506, 368961496469, 1987323655056, 10746633315501, 58321460916482, 317537398625945
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| The subsequence of primes begins: 2, 5, 61, no more through a(30). [From Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 12 2010]
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LINKS
| Guo-Niu Han, Enumeration of Standard Puzzles
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FORMULA
| G.f.=[1+z-sqrt(1-6z+z^2)]/[4z(1-z)].
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MAPLE
| G:=(1+z-sqrt(1-6*z+z^2))/4/z/(1-z): Gser:=series(G, z=0, 29): 1, seq(coeff(Gser, z^n), n=1..27);
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CROSSREFS
| Cf. A001003.
Sequence in context: A012051 A012159 A009736 * A178123 A138265 A000111
Adjacent sequences: A104855 A104856 A104857 * A104859 A104860 A104861
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KEYWORD
| nonn
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AUTHOR
| Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 24 2005
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