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Search: id:A006898
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| A006898 |
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a(n) = Sum_{k=0..n} C(n,k)*2^(k*(k+1)/2).
(Formerly M2958)
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+0
3
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| 1, 3, 13, 95, 1337, 38619, 2310533, 283841911, 70927591153, 35812691480115, 36383765777442685, 74185239630793429775, 303119284294591169426729, 2479814853198140771706795531, 40599509058360322571947638063605
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Number of hierarchical quadratic models on n factors (first differences of A006896).
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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PROGRAM
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(PARI) a(n)=sum(k=0, n, binomial(n, k)*2^(k*(k+1)/2)) - Paul D. Hanna (pauldhanna(AT)juno.com), Apr 10 2009
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CROSSREFS
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Cf. A006896, A135748.
Sequence in context: A116434 A034513 A098462 this_sequence A129375 A085023 A144276
Adjacent sequences: A006895 A006896 A006897 this_sequence A006899 A006900 A006901
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KEYWORD
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nonn
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AUTHOR
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C. L. Mallows (colinm(AT)research.avayalabs.com)
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EXTENSIONS
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Formula and more terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 20 2003
Edited by N. J. A. Sloane, Apr 12 2009 at the suggestion of Vladeta Jovovic
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