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A233339
Number of tilings of a 4 X 3n rectangle using 4n trominoes of any shape.
3
1, 23, 939, 41813, 1895145, 86208957, 3924499731, 178682349823, 8135650498647, 370429531112741, 16866286184557689, 767950873073579951, 34966119230441665595, 1592067343861413081837, 72489555274710984629691, 3300573714050654978094583, 150280779093325614402294089
OFFSET
0,2
LINKS
Wikipedia, Tromino
FORMULA
G.f.: (-x^14 +45*x^13 -790*x^12 +7195*x^11 -37791*x^10 +120544*x^9 -241021*x^8 +307384*x^7 -251359*x^6 +131039*x^5 -42817*x^4 +8472*x^3 -952*x^2 +53*x -1) / (x^15 -56*x^14 +1223*x^13 -13643*x^12 +87066*x^11 -338409*x^10 +836269*x^9 -1345297*x^8 +1419177*x^7 -976456*x^6 +431092*x^5 -118633*x^4 +19424*x^3 -1761*x^2 +76*x -1).
CROSSREFS
Trisection of column k=4 of A233320.
Sequence in context: A081731 A335496 A183523 * A008961 A232757 A139193
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Dec 07 2013
STATUS
approved