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 A001659 Expansion of bracket function. (Formerly M1433 N0567) 7
 1, 1, -1, 2, -5, 13, -33, 80, -184, 402, -840, 1699, -3382, 6750, -13716, 28550, -60587, 129579, -275915, 579828, -1197649, 2431775, -4870105, 9672634, -19173013, 38151533, -76521331, 154941608, -316399235, 649807589, -1337598675, 2751021907, -5640238583, 11513062785, -23389948481, 47310801199, -95345789479, 191616365385 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Inverse binomial transform of A006218. REFERENCES N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 H. W. Gould, Binomial coefficients, the bracket function and compositions with relatively prime summands, Fib. Quart. 2, issue 4, (1964), 241-260. FORMULA a(n) = Sum_{j=0..n} ((-1)^(n-j)*binomial(n,j)*Sum_{k=1..j} floor(j/k)). G.f.: Sum_{k>0} x^k/((1+x)^k-x^k). G.f.: Sum_{k>0} tau(k)*x^k/(1+x)^k. - Vladeta Jovovic, Jun 24 2003 G.f.: sum(n>=1, z^n/(1-z^n)) (Lambert series) where z=x/(1+x). - Joerg Arndt, Jan 30 2011 MATHEMATICA Table[Sum[(-1)^(n - k)*Binomial[n, k]*Sum[Floor[k/j], {j, 1, k}], {k, 0, n}], {n, 1, 50}] (* G. C. Greubel, Jul 02 2017 *) PROG (PARI) a(n)=sum(j=0, n, (-1)^(n-j)*binomial(n, j)*sum(k=1, j, j\k)) (PARI) a(n)=polcoeff(sum(k=1, n, x^k/((1+x)^k-x^k), x*O(x^n)), n) CROSSREFS Cf. A000748, A000749, A000750, A006090, A006218. Equals A038200(n-1) + A038200(n), n>1. Sequence in context: A108890 A220739 A027929 * A088921 A005183 A005348 Adjacent sequences:  A001656 A001657 A001658 * A001660 A001661 A001662 KEYWORD sign AUTHOR EXTENSIONS Edited by Michael Somos, Jun 14 2003 STATUS approved

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Last modified February 18 03:44 EST 2020. Contains 332006 sequences. (Running on oeis4.)