A238558 - OEIS

A238558

Number T(n,k) of equivalence classes of ways of placing k 3 X 3 tiles in an n X 8 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 #18 May 29 2017 21:11:51

%S 1,3,4,1,3,8,1,6,18,1,6,36,32,13,1,9,64,128,87,1,9,100,308,332,1,12,

%T 146,647,1118,451,68,1,12,200,1160,3022,2756,824,1,15,264,1958,6882,

%U 10076,5009,1,15,336,3020,13798,28774,24237,4774,346

%N Number T(n,k) of equivalence classes of ways of placing k 3 X 3 tiles in an n X 8 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 Andrew Howroyd, <a href="/A238558/b238558.txt">Table of n, a(n) for n = 3..971</a>

%H Christopher Hunt Gribble, <a href="/A238009/a238009_1.cpp.txt">C++ program</a>

%e The first 8 rows of T(n,k) are:

%e .\ k 0 1 2 3 4 5 6

%e n

%e 3 1 3 4

%e 4 1 3 8

%e 5 1 6 18

%e 6 1 6 36 32 13

%e 7 1 9 64 128 87

%e 8 1 9 100 308 332

%e 9 1 12 146 647 1118 451 68

%e 10 1 12 200 1160 3022 2756 824

%o (C++) See Gribble link.

%Y Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550-A238552, A228166, A238555, A238556, A228167, A238557, A238559, A228168, A238581-A238583, A228169, A238586, A238592.

%K tabf,nonn

%O 3,2

%A _Christopher Hunt Gribble_, Feb 28 2014

%E Terms corrected and xrefs updated by _Christopher Hunt Gribble_, Apr 27 2015

%E Terms a(41) and beyond from _Andrew Howroyd_, May 29 2017