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 A257523 #9 May 29 2017 21:16:25
%S A257523 1,2,1,2,1,4,1,4,1,6,6,1,6,14,1,8,28,1,8,44,1,10,66,20,1,10,90,64,1,
%T A257523 12,120,168,1,12,152,320,1,14,190,572,72,1,14,230,896,328,1,16,276,
%U A257523 1360,984,1,16,324,1920,2264,1,18,378,2660,4528,272
%N A257523 Number T(n,k) of equivalence classes of ways of placing k 4 X 4 tiles in an n X 7 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=4, 0<=k<=floor(n/4), read by rows.
%H A257523 Andrew Howroyd, <a href="/A257523/b257523.txt">Table of n, a(n) for n = 4..860</a>
%H A257523 Christopher Hunt Gribble, <a href="/A238009/a238009_1.cpp.txt">C++ program</a>
%e A257523 The first 9 rows of T(n,k) are:
%e A257523 .\ k 0 1 2 3
%e A257523 n
%e A257523 4 1 2
%e A257523 5 1 2
%e A257523 6 1 4
%e A257523 7 1 4
%e A257523 8 1 6 6
%e A257523 9 1 6 14
%e A257523 10 1 8 28
%e A257523 11 1 8 44
%e A257523 12 1 10 66 20
%e A257523 13 1 10 90 64
%e A257523 14 1 12 120 168
%e A257523 15 1 12 152 320
%o A257523 (PARI)
%o A257523 T(n,k)={(4^k*binomial(n-3*k,k) + ((n%2==0||k%2==0)+(k%2==0)+(k==0)) * 4^((k+1)\2)*binomial((n-3*k-(k%2)-(n%2))/2,k\2))/4}
%o A257523 for(n=4,15,for(k=0,(n\4), print1(T(n,k), ", "));print) \\ _Andrew Howroyd_, May 29 2017
%Y A257523 Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550, A238551, A238552, A228166, A238555, A238556, A228167, A238557, A238558, A238559, A228168, A238581, A238582, A238583, A228169, A238586, A238592
%K A257523 tabf,nonn
%O A257523 4,2
%A A257523 _Christopher Hunt Gribble_, Apr 27 2015
%E A257523 Terms a(24) and beyond by _Andrew Howroyd_, May 29 2017