A238581 Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 9 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=4*floor(n/2), read by rows.

1, 4, 12, 10, 3, 1, 4, 24, 40, 22, 1, 8, 65, 230, 467, 476, 269, 70, 9, 1, 8, 109, 641, 2281, 4424, 4718, 2409, 473, 1, 12, 182, 1479, 7644, 24024, 47022, 56226, 41000, 17834, 4545, 625, 39, 1, 12, 258, 2762, 19347, 86536, 255552, 495547, 625705, 499314, 239254, 61732, 6533

Offset

2,2

Links

Andrew Howroyd, Table of n, a(n) for n = 2..991

Christopher Hunt Gribble, C++ program

Example

The first 4 rows of T(n,k) are:
.\ k  0     1     2     3     4     5     6     7     8
n
2     1     4    12    10     3
3     1     4    24    40    22
4     1     8    65   230   467   476   269    70     9
5     1     8   109   641  2281  4424  4718  2409   473

Prog

(C++) See Gribble link.

Crossrefs

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, A238582, A238583, A228169, A238586, A238592.

Sequence in context: A334768 A247327 A348419 * A063608 A074258 A253137

Adjacent sequences: A238578 A238579 A238580 * A238582 A238583 A238584

Keyword

tabf,nonn

Author

Christopher Hunt Gribble, Mar 01 2014

Extensions

Terms corrected and xrefs updated by Christopher Hunt Gribble, Apr 27 2015

Terms a(43) and beyond from Andrew Howroyd, May 29 2017

Status

approved