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 A006898 a(n) = Sum_{k=0..n} C(n,k)*2^(k*(k+1)/2). (Formerly M2958) 2
 1, 3, 13, 95, 1337, 38619, 2310533, 283841911, 70927591153, 35812691480115, 36383765777442685, 74185239630793429775, 303119284294591169426729, 2479814853198140771706795531, 40599509058360322571947638063605 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of hierarchical quadratic models on n factors (first differences of A006896). REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS PROG (PARI) a(n)=sum(k=0, n, binomial(n, k)*2^(k*(k+1)/2)) - Paul D. Hanna, Apr 10 2009 CROSSREFS Cf. A006896, A135748. Sequence in context: A243243 A274052 A183283 * A277492 A275528 A129375 Adjacent sequences:  A006895 A006896 A006897 * A006899 A006900 A006901 KEYWORD nonn AUTHOR EXTENSIONS Formula and more terms from Vladeta Jovovic, Sep 20 2003 Edited by N. J. A. Sloane, Apr 12 2009 at the suggestion of Vladeta Jovovic STATUS approved

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