A248102 Number of tilings of a 5 X 2n rectangle using 2n pentominoes of shapes N, Y.
1, 0, 0, 18, 24, 238, 842, 4360, 25900, 112178, 613140, 2941170, 14789274, 74895336, 369603312, 1866863986, 9294391952, 46543456838, 233028690018, 1164275409976, 5830080180396, 29149585256266, 145845002931724, 729627382873090, 3649578988919810
Offset: 0
Keywords
Examples
a(3) = 18: ._______._._. .___._______. .___._______. |_. .___| | | |_. |___. ._| |_. |___. ._| | |_| | ._| | | |_____|_| | | |_____|_| | | ._| | |_. | | |___. ._| | | |___. |_. | | | ._|_| |_| | ._| |_|_. | | ._| |___| | |_|_|_______| (*2) |_|_______|_| (*8) |_|_______|_| (*8) .
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
- Wikipedia, Pentomino
Formula
G.f.: (8*x^15 -52*x^14 -64*x^13 +1087*x^12 -2822*x^11 +2369*x^10 +810*x^9 -2047*x^8 +300*x^7 +122*x^6 +208*x^5 +x^4 +6*x^3 +9*x^2 +2*x -1) / (24*x^15 +4*x^14 -680*x^13 +2673*x^12 -4212*x^11 +2139*x^10 +1574*x^9 -2141*x^8 +456*x^7 -160*x^6 +236*x^5 -11*x^4 +24*x^3 +9*x^2 +2*x -1).