A238550 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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

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