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 A008812 Expansion of (1+x^5)/((1-x)^2*(1-x^5)). 12
 1, 2, 3, 4, 5, 8, 11, 14, 17, 20, 25, 30, 35, 40, 45, 52, 59, 66, 73, 80, 89, 98, 107, 116, 125, 136, 147, 158, 169, 180, 193, 206, 219, 232, 245, 260, 275, 290, 305, 320, 337, 354, 371, 388, 405, 424, 443, 462, 481, 500, 521, 542, 563, 584, 605, 628, 651, 674 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of 0..n arrays of six elements with zero second differences. - R. H. Hardin, Nov 16 2011 Also number of ordered triples (w,x,y) with all terms in {1,...,n+1} and w + 4*x = 5*y. Also the number of 3-tuples (w,x,y) with all terms in {1,...,n+1} and 5*w = 2*x +3*y. - Clark Kimberling, Apr 15 2012 [Corrected by Pontus von Brömssen, Jan 26 2020] a(n) is also the number of 5 boxes polyomino (zig-zag patterns) packing into (n+3) X (n+3) square. See illustration in links. - Kival Ngaokrajang, Nov 10 2013 Also, number of ordered pairs (x,y) with both terms in {1,...,n+1} and x+4*y divisible by 5; or number of ordered pairs (x,y) with both terms in {1,...,n+1} and 2*x+3*y divisible by 5. - Pontus von Brömssen, Jan 26 2020 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Kival Ngaokrajang, Illustration of initial terms Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,1,-2,1). FORMULA G.f.: (1+x^5)/((1-x)^2*(1-x^5)). a(n) = 2*a(n-1) -a(n-2) +a(n-5) -2*a(n-6) +a(n-7). - R. H. Hardin, Nov 16 2011 EXAMPLE For n = 5 there are 8 0..5 arrays of six elements with zero second differences: [0,0,0,0,0,0], [0,1,2,3,4,5], [1,1,1,1,1,1], [2,2,2,2,2,2], [3,3,3,3,3,3], [4,4,4,4,4,4], [5,4,3,2,1,0], [5,5,5,5,5,5]. MAPLE seq(coeff(series((1+x^5)/((1-x)^2*(1-x^5)), x, n+1), x, n), n = 0..65); # G. C. Greubel, Sep 12 2019 MATHEMATICA CoefficientList[Series[(1+x^5)/(1-x)^2/(1-x^5), {x, 0, 65}], x] (* or *) LinearRecurrence[{2, -1, 0, 0, 1, -2, 1}, {1, 2, 3, 4, 5, 8, 11}, 65] (* Harvey P. Dale, Apr 17 2015 *) PROG (PARI) Vec((1+x^5)/(1-x)^2/(1-x^5)+O(x^65)) \\ Charles R Greathouse IV, Sep 25 2012 (MAGMA) R:=PowerSeriesRing(Integers(), 65); Coefficients(R!( (1+x^5)/((1-x)^2*(1-x^5)) )); // G. C. Greubel, Sep 12 2019 (Sage) def A008812_list(prec):     P. = PowerSeriesRing(ZZ, prec)     return P((1+x^5)/((1-x)^2*(1-x^5))).list() A008812_list(65) # G. C. Greubel, Sep 12 2019 (GAP) a:=[1, 2, 3, 4, 5, 8, 11];; for n in [8..65] do a[n]:=2*a[n-1]-a[n-2] +a[n-5]-2*a[n-6]+a[n-7]; od; a; # G. C. Greubel, Sep 12 2019 CROSSREFS Cf. A130497 (first differences). Cf. Expansions of the form (1+x^m)/((1-x)^2*(1-x^m)): A000290 (m=1), A000982 (m=2), A008810 (m=3), A008811 (m=4), this sequence (m=5), A008813 (m=6), A008814 (m=7), A008815 (m=8), A008816 (m=9), A008817 (m=10). Sequence in context: A181341 A174181 A298424 * A343608 A144679 A309679 Adjacent sequences:  A008809 A008810 A008811 * A008813 A008814 A008815 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms added by G. C. Greubel, Sep 12 2019 STATUS approved

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Last modified October 20 22:00 EDT 2021. Contains 348119 sequences. (Running on oeis4.)