cp's OEIS Frontend

A238556 Number T(n,k) of equivalence classes of ways of placing k 3 X 3 tiles in an n X 7 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=3, 0<=k<=2*floor(n/3), read by rows.

%I A238556 #18 May 29 2017 20:37:43
%S A238556 1,3,2,1,3,4,1,6,9,1,6,21,13,4,1,9,39,53,23,1,9,64,128,87,1,12,95,283,
%T A238556 311,91,10,1,12,133,521,891,543,106,1,15,177,917,2118,2030,646,1,15,
%U A238556 228,1444,4424,6000,3295,456,25,1,18,285,2207,8408,15484,13106,4322,473
%N A238556 Number T(n,k) of equivalence classes of ways of placing k 3 X 3 tiles in an n X 7 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=3, 0<=k<=2*floor(n/3), read by rows.
%H A238556 Andrew Howroyd, <a href="/A238556/b238556.txt">Table of n, a(n) for n = 3..971</a>
%H A238556 Christopher Hunt Gribble, <a href="/A238009/a238009_1.cpp.txt">C++ program</a>
%e A238556 The first 5 rows of T(n,k) are:
%e A238556 ./ k    0      1      2      3      4      5      6
%e A238556 n
%e A238556 3       1      3      2
%e A238556 4       1      3      4
%e A238556 5       1      6      9
%e A238556 6       1      6     21     13      4
%e A238556 7       1      9     39     53     23
%e A238556 8       1      9     64    128     87
%e A238556 9       1     12     95    283    311     91     10
%e A238556 10      1     12    133    521    891    543    106
%e A238556 11      1     15    177    917   2118   2030    646
%o A238556 (C++) See Gribble link.
%Y A238556 Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550-A238552, A228166, A238555, A228167, A238557-A238559, A228168, A238581-A238583, A228169, A238586, A238592.
%K A238556 tabf,nonn
%O A238556 3,2
%A A238556 _Christopher Hunt Gribble_, Feb 28 2014
%E A238556 Terms corrected and xrefs updated by _Christopher Hunt Gribble_, Apr 27 2015
%E A238556 Terms a(48) and beyond by _Andrew Howroyd_, May 29 2017