cp's OEIS Frontend

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.

A236915 Number T(n,k) of equivalence classes of ways of placing k 8 X 8 tiles in an n X n square under all symmetry operations of the square; irregular triangle T(n,k), n>=8, 0<=k<=floor(n/8)^2, read by rows.

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%I A236915 #30 Feb 17 2014 12:55:22
%S A236915 1,1,1,1,1,3,1,3,1,6,1,6,1,10,1,10,1,15,25,5,1,1,15,79,65,14,1,21,187,
%T A236915 377,174,1,21,351,1365,1234,1,28,606,3900,6124,1,28,948,9282,23259,1,
%U A236915 36,1426,19726,73204,1,36,2026,38046,199436
%N A236915 Number T(n,k) of equivalence classes of ways of placing k 8 X 8 tiles in an n X n square under all symmetry operations of the square; irregular triangle T(n,k), n>=8, 0<=k<=floor(n/8)^2, read by rows.
%C A236915 The first 16 rows of T(n,k) are:
%C A236915 .\ k  0      1      2      3      4
%C A236915 n
%C A236915 8     1      1
%C A236915 9     1      1
%C A236915 10    1      3
%C A236915 11    1      3
%C A236915 12    1      6
%C A236915 13    1      6
%C A236915 14    1     10
%C A236915 15    1     10
%C A236915 16    1     15     25      5      1
%C A236915 17    1     15     79     65     14
%C A236915 18    1     21    187    377    174
%C A236915 19    1     21    351   1365   1234
%C A236915 20    1     28    606   3900   6124
%C A236915 21    1     28    948   9282  23259
%C A236915 22    1     36   1426  19726  73204
%C A236915 23    1     36   2026  38046 199436
%H A236915 Christopher Hunt Gribble, <a href="/A236915/b236915.txt">Rows n = 8..23, flattened</a>
%H A236915 Christopher Hunt Gribble, <a href="/A236915/a236915.cpp.txt">C++ program</a>
%F A236915 It appears that:
%F A236915 T(n,0) = 1, n>= 8
%F A236915 T(n,1) = (floor((n-8)/2)+1)*(floor((n-8)/2+2))/2, n >= 8
%F A236915 T(c+2*8,2) = A131474(c+1)*(8-1) + A000217(c+1)*floor(8^2/4) + A014409(c+2), 0 <= c < 8, c even
%F A236915 T(c+2*8,2) = A131474(c+1)*(8-1) + A000217(c+1)*floor((8-1)(8-3)/4) + A014409(c+2), 0 <= c < 8, c odd
%F A236915 T(c+2*8,3) = (c+1)(c+2)/2(2*A002623(c-1)*floor((8-c-1)/2) + A131941(c+1)*floor((8-c)/2)) + S(c+1,3c+2,3), 0 <= c < 8 where
%F A236915 S(c+1,3c+2,3) =
%F A236915 A054252(2,3),  c = 0
%F A236915 A236679(5,3),  c = 1
%F A236915 A236560(8,3),  c = 2
%F A236915 A236757(11,3), c = 3
%F A236915 A236800(14,3), c = 4
%F A236915 A236829(17,3), c = 5
%F A236915 A236865(20,3), c = 6
%F A236915 A236915(23,3), c = 7
%e A236915 T(16,3) = 5 because the number of equivalence classes of ways of placing 3 8 X 8 square tiles in an 16 X 16 square under all symmetry operations of the square is 5. The portrayal of an example from each equivalence class is:
%e A236915 ._____________________        _____________________
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%e A236915 |          |          |      |          |          |
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%e A236915 |     .    |     .    |      |     .    |          |
%e A236915 |          |          |      |          |     .    |
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%e A236915 |    .     |          |      |     .    |          |
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%e A236915 |          |          |      |          |          |
%e A236915 |__________|__________|      |__________|__________|
%e A236915 .
%e A236915 ._____________________        _____________________
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%e A236915 |__________|__________|      |__________|__________|
%e A236915 .
%e A236915 ._____________________
%e A236915 |          |          |
%e A236915 |          |          |
%e A236915 |          |          |
%e A236915 |     .    |__________|
%e A236915 |          |          |
%e A236915 |          |          |
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%e A236915 |__________|     .    |
%e A236915 |          |          |
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%e A236915 |     .    |__________|
%e A236915 |          |          |
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%e A236915 |__________|__________|
%Y A236915 Cf. A054252, A236679, A236560, A236757, A236800, A236829, A236865, A236936, A236939.
%K A236915 tabf,nonn
%O A236915 8,6
%A A236915 _Christopher Hunt Gribble_, Feb 01 2014