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 A108577 #17 Feb 17 2025 03:32:13
%S A108577 0,0,0,0,0,0,0,0,0,1,2,5,8,12,16,23,30,40,50,63,76,93,110,132,154,180,
%T A108577 206,238,270,308,346,390,434,485,536,595,654,720,786,861,936,1020,
%U A108577 1104,1197,1290,1393,1496,1610,1724,1848,1972,2108,2244,2392,2540,2700,2860
%N A108577 Number of symmetry classes of 3 X 3 magic squares (with distinct positive entries) having all entries < n.
%C A108577 A magic square has distinct positive integers in its cells, whose sum is the same (the "magic sum") along any row, column, or main diagonal. The symmetries are those of the square. - _Thomas Zaslavsky_, Mar 12 2010
%H A108577 Thomas Zaslavsky, <a href="/A108577/b108577.txt">Table of n, a(n) for n = 1..10000</a>.
%H A108577 Matthias Beck and Thomas Zaslavsky, <a href="https://people.math.binghamton.edu/zaslav/Tpapers/SLSfiles/">Auxiliary files for "Six little squares"</a>.
%H A108577 Matthias Beck and Thomas Zaslavsky, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL13/Zaslavsky/sls.html">Six Little Squares and How their Numbers Grow</a>, Journal of Integer Sequences, 13 (2010), Article 10.6.2.
%H A108577 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,1,-2,2,-2,1,0,-1,2,-1).
%F A108577 G.f.: (x^10*(2*x^2+1)) / ((1-x^6)*(1-x^4)*(1-x)^2).
%F A108577 a(n) is given by a quasipolynomial of period 12.
%e A108577 a(10) = 1 because there is only one symmetry type of 3 X 3 magic square with entries 1,...,9.
%t A108577 LinearRecurrence[{2, -1, 0, 1, -2, 2, -2, 1, 0, -1, 2, -1}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 5}, 58] (* _Mike Sheppard_, Feb 04 2025 *)
%Y A108577 Cf. A108576, A108578, A108579.
%K A108577 nonn,easy
%O A108577 1,11
%A A108577 _Thomas Zaslavsky_, Jun 11 2005