OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1453
Wikipedia, Domino (mathematics)
Wikipedia, Tromino
Index entries for linear recurrences with constant coefficients, signature (3,6,13,0,53,18,69,48,35,-125,-76,-24,38,8,18,1,-3,-1).
FORMULA
G.f.: -(x^15 +2*x^14 +4*x^13 -5*x^12 -9*x^11 -18*x^10 +16*x^9 +5*x^8 +8*x^7 -10*x^6 +13*x^5 -6*x^4 +7*x^3 +3*x^2 +2*x -1) / (x^18 +3*x^17 -x^16 -18*x^15 -8*x^14 -38*x^13 +24*x^12 +76*x^11 +125*x^10 -35*x^9 -48*x^8 -69*x^7 -18*x^6 -53*x^5 -13*x^3 -6*x^2 -3*x +1).
a(n) mod 2 = A133872(n).
EXAMPLE
a(2) = 6:
.___. .___. .___. .___. .___. .___.
| | | |___| | | | |___| | ._| |_. |
| | | |___| |_|_| | | | |_| | | |_|
|_|_| |___| |___| |_|_| |___| |___| .
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Jul 25 2023
STATUS
approved