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A110266 Number of blocks of ON cells in n-th row of triangle generated by Wolfram's "Rule 30". 1
1, 1, 2, 2, 3, 3, 4, 3, 4, 5, 6, 6, 7, 7, 8, 7, 7, 8, 10, 9, 9, 11, 14, 12, 11, 12, 15, 16, 14, 15, 17, 14, 15, 17, 20, 18, 18, 18, 21, 21, 17, 19, 21, 20, 23, 22, 23, 22, 23, 21, 27, 30, 26, 27, 29, 29, 28, 28, 33, 31, 30, 31, 36, 32, 28, 29, 33, 33, 33, 35 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Old name was "Number of trees appearing at n-th generation of a black cell following Wolfram's Rule 30 cellular automaton."

At each generation, "looking back", one can see "behind", groups (sort of black isles) of contiguous black cells which after a while appear to be trees growing. It should be possible to describe each one of them in terms of trees theory.

LINKS

Charlie Neder, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Rule 30.

EXAMPLE

a(1)=1 because one black cell;

a(2)=1 because there are now 3 contiguous black cell connected to the first one, which forms one only black surface;

a(3)=2 because two black cells are now connected to the preceding black surface and another black cell appears, which is isolated, so we have two separate black surfaces: 2.

From Charlie Neder, Feb 06 2019: (Start)

Rule 30 triangle begins:

                     1

                    111

                   11  1

                  11 1111

                 11  1   1

                11 1111 111

               11  1    1  1

              11 1111  111111

             11  1   111     1

and the number of blocks of ON cells in each row is 1, 1, 2, 2, 3, 3, 4, 3, 4, ... (End)

CROSSREFS

Cf. A070950, A051023, A092539, A092540, A070952, A100053, A100054, A100055, A094603, A094604, A000225, A074890.

Sequence in context: A067539 A166312 A138099 * A309067 A205561 A323636

Adjacent sequences:  A110263 A110264 A110265 * A110267 A110268 A110269

KEYWORD

easy,nonn

AUTHOR

Alexandre Wajnberg, Sep 06 2005

EXTENSIONS

New name and a(17)-a(70) from Charlie Neder, Feb 06 2019

STATUS

approved

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Last modified July 21 04:40 EDT 2019. Contains 325189 sequences. (Running on oeis4.)