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A285930
Run lengths of 0's in A282317, the lexicographically first cubefree sequence in {0,1} .
2
2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 1, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 2, 2, 0, 2, 2, 1, 0, 2, 2, 1, 2, 2
OFFSET
1,1
COMMENTS
In other words: Number of 0's before the first '1' and then between two consecutive '1's in A282317.
This sequence is also cubefree: A cube xxx in this sequence would correspond to a cube yyy in A282317, where y is obtained by "decoding" x, i.e., replacing each term x[i] by a run of x[i] "0"s followed by a "1".
Also, a(n) = d(n)-1 where d(n) = b(n)-b(n-1) is the first difference of the sequence b which lists the indices of nonzero terms in A282317 (such that A282317 is the characteristic sequence of b), and b(0) := -1.
EXAMPLE
Sequence A282317 starts with a(1) = 2 '0's, then a '1', then again a(2) = 2 '0's followed by a '1' then a(3) = 1 '0's followed by a '1'. Then again a(4) = 2 '0's followed by a '1' and another a(5) = 2 '0's followed by a '1', then a(6) = 0 '0's before the next '1', i.e., the preceding '1' is immediately followed by another '1'. And so on.
PROG
(PARI) A285930(n, A=A282317_vec(n\.4), c=0)=for(i=1, #A, (A[i]&&c=print1(c", "))||c++)
CROSSREFS
Cf. A282317.
Sequence in context: A051480 A071572 A172176 * A300480 A342870 A143537
KEYWORD
nonn
AUTHOR
M. F. Hasler, May 02 2017
STATUS
approved