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A278874 Number of tilings of a 2 X n rectangle using pentominoes of any shape and monominoes. 2
1, 1, 1, 7, 25, 50, 155, 508, 1343, 3800, 11438, 32525, 92333, 268766, 774302, 2216976, 6392865, 18425916, 52958070, 152425812, 438973764, 1263109849, 3634965137, 10463959311, 30116734921, 86675829307, 249478723992, 718056248229, 2066658063664, 5948257601097 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Wikipedia, Pentomino

FORMULA

G.f.: -(x^10 +x^8 -x^6 -6*x^5 -x^4 -5*x^3 +1) / (x^15 +x^13 -2*x^11 -11*x^10 -2*x^9 -10*x^8 +x^7 +9*x^6 +12*x^5 +8*x^4 +11*x^3 +x -1).

EXAMPLE

a(3) = 7:

._____. ._____. ._____. ._____. ._____. ._____. ._____.

|_|_|_| | |_| | | ._. | |   ._| |_.   | |   |_| |_|   |

|_|_|_| |_____| |_|_|_| |___|_| |_|___| |_____| |_____| .

CROSSREFS

Column k=2 of A278657.

Sequence in context: A147129 A173825 A269589 * A137380 A309901 A094672

Adjacent sequences:  A278871 A278872 A278873 * A278875 A278876 A278877

KEYWORD

nonn,easy

AUTHOR

Alois P. Heinz, Nov 29 2016

STATUS

approved

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Last modified August 1 03:52 EDT 2021. Contains 346384 sequences. (Running on oeis4.)