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
KEYWORD
easy,nonn,changed
AUTHOR
Alexandre Wajnberg, Sep 06 2005
EXTENSIONS
New name and a(17)-a(70) from Charlie Neder, Feb 06 2019
STATUS
approved