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 A238555 Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 7 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=3*floor(n/2), read by rows. 21
 1, 3, 6, 2, 1, 3, 12, 8, 1, 6, 34, 68, 72, 30, 6, 1, 6, 58, 206, 403, 336, 106, 1, 9, 98, 509, 1551, 2505, 2196, 971, 219, 20, 1, 9, 140, 980, 4248, 10592, 15614, 12876, 5462, 900, 1, 12, 198, 1742, 9748, 33644, 73274, 98779, 80661, 37886, 9679, 1258, 72 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 LINKS Andrew Howroyd, Table of n, a(n) for n = 2..953 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     6     2 3     1     3    12     8 4     1     6    34    68    72    30     6 5     1     6    58   206   403   336   106 6     1     9    98   509  1551  2505  2196   971   219    20 7     1     9   140   980  4248 10592 15614 12876  5462   900 PROG (C++) See Gribble link. CROSSREFS Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550, A238551, A238552, A228166, A238556, A228167, A238557, A238558, A238559, A228168, A238581, A238582, A238583, A228169, A238586, A238592. Sequence in context: A058178 A058078 A016551 * A176034 A255051 A145896 Adjacent sequences:  A238552 A238553 A238554 * A238556 A238557 A238558 KEYWORD tabf,nonn AUTHOR Christopher Hunt Gribble, Feb 28 2014 EXTENSIONS Terms corrected and xrefs updated by Christopher Hunt Gribble, Apr 27 2015 STATUS approved

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Last modified February 20 16:42 EST 2020. Contains 332080 sequences. (Running on oeis4.)