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A294960 Snowflake (or E-toothpick) sequence of the second kind (see Comments lines for definition). 1
0, 2, 8, 14, 20, 26, 44, 50, 68, 86, 104, 110, 128, 158, 176, 206, 260, 278, 320, 350, 392, 410, 452, 494, 548, 614 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

Table of n, a(n) for n=0..25.

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

Index entries for sequences related to cellular automata

Index entries for sequences related to toothpick sequences

CROSSREFS

Another version of A161330.

Cf. A139250, A160120, A161328, A294961 (first differences).

Sequence in context: A117104 A082933 A016933 * A101959 A241003 A133229

Adjacent sequences:  A294957 A294958 A294959 * A294961 A294962 A294963

KEYWORD

nonn,more

AUTHOR

Omar E. Pol, Nov 12 2017

STATUS

approved

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Last modified November 15 14:06 EST 2019. Contains 329149 sequences. (Running on oeis4.)