This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A208828 #13 Jul 07 2018 06:16:18 %S A208828 32,609,4390,19657,65134,177097,417204,883409,1720628,3135633,5410378, %T A208828 8921049,14153874,21728505,32416136,47167393,67132584,93694273, %U A208828 128489486,173447145,230812054,303187369,393560188,505349233,642431868,809197169 %N A208828 Number of 7-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero. %C A208828 Row 7 of A208825. %H A208828 R. H. Hardin, <a href="/A208828/b208828.txt">Table of n, a(n) for n = 1..210</a> %F A208828 Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - 8*a(n-3) + 14*a(n-4) - 14*a(n-6) + 8*a(n-7) + 3*a(n-8) - 4*a(n-9) + a(n-10). %F A208828 Empirical g.f.: x*(32 + 481*x + 2050*x^2 + 4180*x^3 + 4100*x^4 + 2126*x^5 + 462*x^6 + 28*x^7 - 4*x^8 + x^9) / ((1 - x)^7*(1 + x)^3). - _Colin Barker_, Jul 07 2018 %e A208828 Some solutions for n=3: %e A208828 -3 -3 -2 -3 -3 -3 -3 -3 -3 -3 -3 -2 -3 -1 -3 -2 %e A208828 1 -1 -2 -1 2 -2 1 -1 -2 -2 3 -2 2 -1 -1 -1 %e A208828 -1 3 0 -2 0 2 -1 1 1 -1 0 -1 -2 0 -1 1 %e A208828 -1 1 1 -1 1 1 2 1 3 2 -2 -1 0 0 1 -1 %e A208828 1 0 2 2 -2 2 -3 1 -3 2 -2 3 1 1 1 -1 %e A208828 2 -2 -1 3 -1 -2 1 2 3 3 1 0 0 1 2 3 %e A208828 1 2 2 2 3 2 3 -1 1 -1 3 3 2 0 1 1 %Y A208828 Cf. A208825. %K A208828 nonn %O A208828 1,1 %A A208828 _R. H. Hardin_, Mar 01 2012