cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A350728 a(n) = A350633(n)/4.

Original entry on oeis.org

2, 3, 6, 3, 7, 9, 14, 3, 7, 9, 19, 11, 23, 23, 41, 4, 7, 9, 19, 11, 23, 23, 49, 19, 27, 29, 51, 45, 59, 57, 106, 9, 7, 9, 19, 11, 23, 23, 49, 19, 27, 29, 51, 45, 59, 57, 123, 39, 39, 39, 63, 55, 71, 67, 135, 79, 87, 99, 127, 123, 155, 143, 269, 40, 7, 9, 19
Offset: 2

Views

Author

Rémy Sigrist, Jan 11 2022, after a suggestion from Hugo Pfoertner

Keywords

Comments

Also, first differences of A350727.

Examples

			a(8) = A350633(8)/4 = 56/4 = 14.

Links

Crossrefs

Cf. A350633, A350727.

A350632 a(n) is the total number of ON cells at stage n of a cellular automaton where cells are turned ON when they have one or two neighbors ON (see Comments for precise definition).

Original entry on oeis.org

0, 1, 9, 21, 45, 57, 85, 121, 177, 189, 217, 253, 329, 373, 465, 557, 721, 737, 765, 801, 877, 921, 1013, 1105, 1301, 1377, 1485, 1601, 1805, 1985, 2221, 2449, 2873, 2909, 2937, 2973, 3049, 3093, 3185, 3277, 3473, 3549, 3657, 3773, 3977, 4157, 4393, 4621, 5113
Offset: 0

Views

Author

Rémy Sigrist, Jan 08 2022

Keywords

Comments

On the infinite square grid, start with all cells OFF.
Turn a single cell to the ON state.
At each subsequent step, each cell with exactly one or two neighbors ON is turned ON, and everything that is already ON remains ON.
Here "neighbor" refers to the eight adjacent and diagonally adjacent cells in the Moore neighborhood.

Examples

			The first 5 generations can be depicted as follows:
         . . . . . . . . . . .
         . 5 5 . . . . . 5 5 .
         . 5 4 4 4 4 4 4 4 5 .
         . . 4 3 3 . 3 3 4 . .
         . . 4 3 2 2 2 3 4 . .
         . . 4 . 2 1 2 . 4 . .
         . . 4 3 2 2 2 3 4 . .
         . . 4 3 3 . 3 3 4 . .
         . 5 4 4 4 4 4 4 4 5 .
         . 5 5 . . . . . 5 5 .
         . . . . . . . . . . .
- so a(0) = 0,
     a(1) = 0 + 1 = 1,
     a(2) = 1 + 8 = 9,
     a(3) = 9 + 12 = 21,
     a(4) = 21 + 24 = 45,
     a(5) = 45 + 12 = 57.

Links

Crossrefs

Cf. A147562, A151725, A160414, A256530, A350633, A350639.
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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