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 A009563 E.g.f. sin(x/cosh(x)) (odd powers only). 0
 1, -4, 56, -1688, 84160, -6141312, 613282944, -80158806016, 13267800137728, -2710082835353600, 669033814167273472, -196220826200422416384, 67398310755666413387776, -26784943833122921085534208 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA a(n)=2*sum(m=0..n-1, binomial(2*n+1,2*m+1)*(sum(j=0..(n-m), binomial(m+j-1/2,j)*4^(n-m-j)*sum(i=0..j, (i-j)^(2*n-2*m)*binomial(2*j,i)*(-1)^(m+j-i)))))+(-1)^n. [Vladimir Kruchinin, Jun 16 2011] PROG (Maxima) a(n):=2*sum(binomial(2*n+1, 2*m+1)*(sum(binomial(m+j-1/2, j)*4^(n-m-j)*sum((i-j)^(2*n-2*m)*binomial(2*j, i)*(-1)^(m+j-i), i, 0, j), j, 0, (n-m))), m, 0, n-1)+(-1)^n; [Vladimir Kruchinin, Jun 16 2011] CROSSREFS Sequence in context: A009558 A113583 A174489 * A111849 A009159 A013055 Adjacent sequences:  A009560 A009561 A009562 * A009564 A009565 A009566 KEYWORD sign AUTHOR EXTENSIONS Extended with signs Mar 15 1997 by Olivier Gerard. STATUS approved

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