A211964 -id:A211964 - cp's OEIS frontend

A211976 First differences of the E-toothpick sequence A211964.

1, 1, 1, 2, 1, 2, 2, 2, 3, 2, 3, 4, 1, 2, 2, 3, 5, 3, 7, 4, 5, 7, 4, 6, 7, 2, 4, 4, 5, 8, 6, 11, 8, 8, 9, 6, 7, 8, 8, 8, 5, 6, 10, 7, 11, 11, 9, 9, 12, 9, 14, 9, 10, 14, 11, 14, 10, 9, 9, 11, 16, 16, 13, 12, 11, 14, 14, 16, 17, 10, 10, 14

Offset: 1

Omar E. Pol, Dec 15 2012

nonn

Number of E-toothpicks added at n-th stage to the triangular structure of A211964.

Cf. A139250, A139251, A161330, A211964.

a(n) = ((A161331(n+1)/6) + 1)/2.

A220478 Equilateral triangle from the snowflake (or E-toothpick) structure of A161330 (see Comments lines for definition).

Original entry on oeis.org

0, 2, 4, 6, 10, 12, 16, 20, 24, 30, 34, 40, 48, 50, 54, 58, 64, 74, 80, 94, 102, 112, 126, 134, 146, 160, 164, 172, 180, 190, 206, 218, 240, 256, 272, 290, 302, 316, 332, 348, 364, 374, 386, 406, 420, 442, 464, 482, 500, 524, 542, 570, 588, 608, 636, 658, 686, 706, 724, 742

Offset: 0

Omar E. Pol, Dec 22 2012

nonn

It appears that if n >> 1 the structure looks like an equilateral triangle, which is essentially one of the six wedges of the E-toothpick (or snowflake) structure of A161330. The sequence gives the number of E-toothpicks in the structure after n stages. A220498 (the first differences) gives the number added at the n-th round. For more information and some illustrations see A161330. For the E-toothpick right triangle see A211964.

N. J. A. Sloane, A single E-toothpick
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

Cf. A139250, A161328, A160120, A161330, A161336, A211964, A213360, A220498.

a(n) = n + (A161330(n) - 2)/6, n >= 1.

a(n) = n + A161336(n) = 2*A211964(n).

cp's OEIS Frontend

A211976 First differences of the E-toothpick sequence A211964.

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