A238582 - OEIS

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A238582

Number T(n,k) of equivalence classes of ways of placing k 3 X 3 tiles in an n X 9 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=3, 0<=k<=2*floor(n/3), read by rows.

12

1, 4, 6, 1, 1, 4, 12, 3, 1, 8, 28, 10, 1, 8, 54, 82, 49, 8, 1, 1, 12, 95, 283, 311, 91, 10, 1, 12, 146, 647, 1118, 451, 68, 1, 16, 212, 1300, 3380, 3076, 1200, 209, 20, 1, 1, 16, 288, 2260, 8443, 13336, 9364, 2819, 387, 20

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

OFFSET

3,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 3..989

Christopher Hunt Gribble, C++ program

EXAMPLE

The first 9 rows of T(n,k) are:

.\ k 0 1 2 3 4 5 6 7 8 9

n

3 1 4 6 1

4 1 4 12 3

5 1 8 28 10

6 1 8 54 82 49 8 1

7 1 12 95 283 311 91 10

8 1 12 146 647 1118 451 68

9 1 16 212 1300 3380 3076 1200 209 20 1

10 1 16 288 2260 8443 13336 9364 2819 387 20

11 1 20 379 3709 18203 42412 44599 19051 3682 282

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, A238581, A238583, A228169, A238586, A238592.

Sequence in context: A262562 A107951 A019646 * A154748 A190282 A164833

Adjacent sequences: A238579 A238580 A238581 * A238583 A238584 A238585

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(46) and beyond from Andrew Howroyd, May 29 2017

STATUS

approved