OFFSET
0,2
COMMENTS
The orbit of 1 under this rule is A006977.
The substitution rules 000 -> 0 and 100 -> 0 ensure that no (even or odd) input value can ever extend / "propagate" to the right, therefore it is not required to consider the additional digit to the right of input bit 0 (i.e., the cell which would have this bit 0 as left neighbor), as one would usually do in the context of elementary cellular automata (cf., e.g., A292680 vs. A292681).
LINKS
Eric Weisstein's World of Mathematics, Elementary Cellular Automaton
EXAMPLE
n | a(n)
0 = 0[2] | 0[2] = 0
1 = 1[2] | 11[2] = 3 (bits below 001 and 01(0) are on)
2 = 10[2] | 110[2] = 6 (1 below 001 and 010, 0 below 10(0))
3 = 11[2] | 101[2] = 5 (1 below 001 and 11(0), 0 below 011.)
4 = 100[2] | 1100[2] = 12 (as n = 1 and n = 2, shifted left once more)
5 = 101[2] | 1111[2] = 15 (1 below 001, 010 (twice) and 101)
6 = 110[2] | 1010[2] = 10 (as n = 3, shifted left once)
7 = 111[2] | 1011[2] = 11 (1 below 001, 111 and 11(0), 0 below 011).
PROG
(PARI) apply( A292682(n, r=230)=sum(i=0, logint(!n+n<<=1, 2)+1, bittest(r, bitand(n>>i, 7))<<i), [0..60])
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
M. F. Hasler, Oct 09 2017
STATUS
approved