cp's OEIS Frontend

This has essentially the same rules as the snowflake sequence A161330, but here there is an additional rule: there are no E-toothpicks of the same generation that share the endpoint of two parallel components.

The structure is lighter than the structure of A161330 from which differs at a(7).

Note that, on the infinite triangular grid, an E-toothpick can be represented as a polyedge with three components. In this case, at the n-th round, the structure is a polyedge with 3*a(n) components.

An E-toothpick looks like a bird's footprint (or more generally a dinosaur's footprint).

a(n) gives the number of E-toothpicks in the structure after n rounds.

A294961(n) is the number of E-toothpicks added at the n-th round, n >= 1. - Omar E. Pol, Apr 15 2018