a(n) is the number of free, tree-like polyiamonds, of size 3*n+1, with 120-degree rotational symmetry formed of a central triangle and identical, non-intersecting snakes leading from each of its sides.
A358709
a(n) is the number of free, tree-like polyiamonds, of size 3*n+1, with 120-degree rotational symmetry formed of a central triangle and identical, non-intersecting snakes leading from each of its sides.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =6a(6) =11a(7) =20a(8) =37a(9) =66a(10) =119a(11) =217a(12) =391a(13) =706a(14) =1274a(15) =2289a(16) =4133a(17) =7435a(18) =13384a(19) =24068
External references
- oeis: A358709