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 A154615 a(n) = A022998(n)^2. 6
 0, 1, 16, 9, 64, 25, 144, 49, 256, 81, 400, 121, 576, 169, 784, 225, 1024, 289, 1296, 361, 1600, 441, 1936, 529, 2304, 625, 2704, 729, 3136, 841, 3600, 961, 4096, 1089, 4624, 1225, 5184, 1369, 5776, 1521, 6400, 1681, 7056, 1849, 7744, 2025, 8464, 2209, 9216 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Multiplicative because A022998 is. - Andrew Howroyd, Jul 25 2018 LINKS G. C. Greubel, Table of n, a(n) for n = 0..5000 Index entries for linear recurrences with constant coefficients, signature (0,3,0,-3,0,1). FORMULA Denominators of 1/4 - 1/(2n)^2, if n>0. a(2n+1) = A016754(n). a(2n) = 16*A000290(n). a(n) = A061038(2*n) (bisection). a(n) = 3*a(n-2) - 3*a(n-4) + a(n-6). G.f.: x*(1+16*x+6*x^2+16*x^3+x^4)/((1-x)^3*(1+x)^3). From G. C. Greubel, Jul 20 2017: (Start) a(n) = (1/2)*(5 + 3*(-1)^n)*n^2. E.g.f.: x*( (4*x +1)*cosh(x) + (x+4)*sinh(x) ). (End) MATHEMATICA Join[{0}, Denominator[Table[(1/4)*(1 - 1/n^2), {n, 1, 50}]]] (* or *) Table[(1/2)*(5 + 3*(-1)^n)*n^2 {n, 0, 50}] (* G. C. Greubel, Jul 20 2017 *) PROG (PARI) for(n=0, 50, print1((1/2)*(5 + 3*(-1)^n)*n^2, ", ")) \\ G. C. Greubel, Jul 20 2017 CROSSREFS Sequence in context: A281719 A103167 A303317 * A040242 A306378 A232999 Adjacent sequences:  A154612 A154613 A154614 * A154616 A154617 A154618 KEYWORD nonn,easy,mult AUTHOR Paul Curtz, Jan 13 2009 EXTENSIONS Edited, offset set to 1, and extended by R. J. Mathar, Sep 07 2009 a(0) added Oct 21 2009 STATUS approved

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Last modified October 15 17:24 EDT 2019. Contains 328037 sequences. (Running on oeis4.)