A238550 Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 6 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=3*floor(n/2), read by rows.

1, 3, 4, 1, 1, 3, 8, 3, 1, 6, 23, 33, 22, 6, 1, 1, 6, 40, 101, 125, 54, 10, 1, 9, 68, 262, 534, 532, 276, 74, 12, 1, 1, 9, 98, 509, 1551, 2505, 2196, 971, 219, 20, 1, 12, 139, 927, 3731, 8772, 12069, 9506, 4366, 1160, 179, 16, 1, 1, 12, 182, 1479, 7644, 24024

Offset

2,2

Links

Andrew Howroyd, Table of n, a(n) for n = 2..953 (terms n=2..69 from Christopher Hunt Gribble)

Christopher Hunt Gribble, C++ program

Example

The first 6 rows of T(n,k) are:
.\ k  0     1     2     3     4     5     6     7     8     9
n
2     1     3     4     1
3     1     3     8     3
4     1     6    23    33    22     6     1
5     1     6    40   101   125    54    10
6     1     9    68   262   534   532   276    74    12     1
7     1     9    98   509  1551  2505  2196   971   219    20

Prog

(C++) See Gribble link.

Crossrefs

Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238551, A238552, A228166, A238555, A238556, A228167, A238557-A238559, A228168, A238581-A238583, A228169, A238586, A238592.

Sequence in context: A131107 A046547 A016453 * A275886 A158572 A083532

Adjacent sequences: A238547 A238548 A238549 * A238551 A238552 A238553

Keyword

tabf,nonn

Author

Christopher Hunt Gribble, Feb 28 2014

Extensions

Terms corrected and xrefs updated by Christopher Hunt Gribble, Apr 26 2015

Status

approved