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 A097992 G.f.: 1/((1-x)*(1-x^6)) = 1/ ( (1+x)*(x^2-x+1)*(1+x+x^2)*(x-1)^2 ). 3
 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 LINKS G. Nebe, E. M. Rains and N. J. A. Sloane, Self-Dual Codes and Invariant Theory, Springer, Berlin, 2006. Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,1,-1). FORMULA Molien series is 1/((1-x^2)*(1-x^12)). a(n)= Sum_{k=0..n} 1/90*{-14*[k mod 6]+[(k+1) mod 6]+[(k+2) mod 6]+[(k+3) mod 6]+[(k+4) mod 6]+16*[(k+5) mod 6]}, with n>=0. - Paolo P. Lava, May 15 2007 a(n)=1+floor(n/6) a(n)=1+(6*n-15+3*(-1)^n+12*sin[(2*n+1)*Pi/6]+4*sqrt(3)*sin[(2*n+1)*Pi/3])/36 CROSSREFS Apart from initial terms, same as A054895. Sequence in context: A133876 A152467 A242602 * A195177 A147583 A054895 Adjacent sequences:  A097989 A097990 A097991 * A097993 A097994 A097995 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 07 2004 STATUS approved

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