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 A027026 a(n) = T(n,n+4), T given by A027023. 4
 1, 25, 85, 215, 477, 985, 1949, 3755, 7113, 13329, 24805, 45959, 84917, 156625, 288573, 531323, 977873, 1799273, 3310133, 6089111, 11200525, 20601961, 37893981, 69699051, 128197785, 235793825, 433693893, 797688967, 1467180389 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,2 LINKS G. C. Greubel, Table of n, a(n) for n = 4..1003 Index entries for linear recurrences with constant coefficients, signature (4,-5,2,-1,2,-1). FORMULA G.f.: x^4*(1 +21*x -10*x^2 -2*x^3 -7*x^4 +5*x^5)/((1-x)^3*(1-x-x^2-x^3)). - Ralf Stephan, Feb 11 2004 a(n) = A000213(n+4) -2*n*(n+3), n>3. - R. J. Mathar, Jun 24 2020 MAPLE seq(coeff(series(x^4*(1 +21*x -10*x^2 -2*x^3 -7*x^4 +5*x^5)/((1-x)^3*(1-x-x^2-x^3)), x, n+1), x, n), n = 4..40); # G. C. Greubel, Nov 04 2019 MATHEMATICA Drop[CoefficientList[Series[x^4*(1+21*x-10*x^2-2*x^3-7*x^4 +5*x^5)/((1-x)^3*(1-x-x^2-x^3)), {x, 0, 40}], x], 4] (* or *) LinearRecurrence[{4, -5, 2, -1, 2, -1}, {1, 25, 85, 215, 477, 985}, 40] (* G. C. Greubel, Nov 04 2019 *) PROG (PARI) my(x='x+O('x^40)); Vec(x^4*(1 +21*x -10*x^2 -2*x^3 -7*x^4 +5*x^5)/((1-x)^3*(1-x-x^2-x^3))) \\ G. C. Greubel, Nov 04 2019 (MAGMA) R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( x^4*(1 +21*x -10*x^2 -2*x^3 -7*x^4 +5*x^5)/((1-x)^3*(1-x-x^2-x^3)) )); // G. C. Greubel, Nov 04 2019 (Sage) def A027026_list(prec):     P. = PowerSeriesRing(ZZ, prec)     return P(x^4*(1 +21*x -10*x^2 -2*x^3 -7*x^4 +5*x^5)/((1-x)^3*(1-x-x^2-x^3))).list() a=A027026_list(50); a[4:] # G. C. Greubel, Nov 04 2019 (GAP) a:=[1, 25, 85, 215, 477, 985];; for n in [7..40] do a[n]:=4*a[n-1] -5*a[n-2]+2*a[n-3]-a[n-4]+2*a[n-5]-a[n-6]; od; a; # G. C. Greubel, Nov 04 2019 CROSSREFS Sequence in context: A166080 A081272 A318293 * A251195 A087240 A044212 Adjacent sequences:  A027023 A027024 A027025 * A027027 A027028 A027029 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified November 30 18:37 EST 2021. Contains 349424 sequences. (Running on oeis4.)