Number of stacked directed animals on the triangular lattice.

Terms

a(0) =1a(1) =3a(2) =11a(3) =44a(4) =184a(5) =789a(6) =3435a(7) =15100a(8) =66806a(9) =296870a(10) =1323318a(11) =5911972a(12) =26455294a(13) =118528793a(14) =531540891a(15) =2385375732a(16) =10710619014a(17) =48112492938a(18) =216195753066a(19) =971744791032