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A231145 Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 5 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=n-n%2, read by rows. 22
1, 2, 2, 1, 2, 4, 1, 4, 13, 10, 4, 1, 4, 23, 35, 23, 1, 6, 40, 101, 125, 54, 10, 1, 6, 58, 206, 403, 336, 106, 1, 8, 83, 392, 1056, 1438, 956, 240, 25, 1, 8, 109, 641, 2281, 4424, 4718, 2409, 473, 1, 10, 142, 1011, 4429, 11370, 17252, 14478, 6094, 1020, 70 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 2..967 (terms n=2..71 from Christopher Hunt Gribble)

Christopher Hunt Gribble, C++ program

EXAMPLE

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

.\ k  0     1     2     3     4     5     6     7     8

n

2     1     2     2

3     1     2     4

4     1     4    13    10     4

5     1     4    23    35    23

6     1     6    40   101   125    54    10

7     1     6    58   206   403   336   106

8     1     8    83   392  1056  1438   956   240    25

9     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, A231473, A231568, A232440, A228165, A238550, A238551, A238552, A228166, A238555, A238556, A228167, A238557, A238558, A238559, A228168, A238581, A238582, A238583, A228169, A238586, A238592.

Sequence in context: A125912 A127677 A238009 * A007427 A048106 A304649

Adjacent sequences:  A231142 A231143 A231144 * A231146 A231147 A231148

KEYWORD

tabf,nonn

AUTHOR

Christopher Hunt Gribble, Feb 23 2014

EXTENSIONS

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

STATUS

approved

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Last modified February 19 22:36 EST 2020. Contains 332061 sequences. (Running on oeis4.)