A233339 Number of tilings of a 4 X 3n rectangle using 4n trominoes of any shape.

1, 23, 939, 41813, 1895145, 86208957, 3924499731, 178682349823, 8135650498647, 370429531112741, 16866286184557689, 767950873073579951, 34966119230441665595, 1592067343861413081837, 72489555274710984629691, 3300573714050654978094583, 150280779093325614402294089

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..600

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

Adjacent sequences: A233336 A233337 A233338 * A233340 A233341 A233342

Keyword

nonn,easy

Author

Alois P. Heinz, Dec 07 2013

Status

approved