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A305393
First differences of A140102.
9
1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1
OFFSET
1,2
COMMENTS
Although initially this agrees with A293630, the sequences are distinct.
From Michel Dekking, Mar 18 2019: (Start)
Let x be the tribonacci word x = A092782 = 1,2,1,3,1,2,1,1,...
Consider the morphism delta:
1 -> 1112,
2 -> 112,
3 -> 12.
Conjecture: (a(n)) = 12 delta(x).
(End)
Conjecture: This sequence (prefixed by 1 since A140102 should really begin with 0) is 1.TTW(1,2,1) where TTW is the ternary tribonacci word defined in A080843, or equally it is THETA(1,2,1), where THETA is defined in A275925. - N. J. A. Sloane, Mar 19 2019
All these conjectures are now theorems - see the Dekking et al. paper. - N. J. A. Sloane, Jul 22 2019
LINKS
F. Michel Dekking, Jeffrey Shallit, and N. J. A. Sloane, Queens in exile: non-attacking queens on infinite chess boards, Electronic J. Combin., 27:1 (2020), #P1.52.
FORMULA
a(n) = A140102(n+1)-A140102(n), n >= 1.
CROSSREFS
For first differences of A140100, A140101, A140102, A140103 see A305392, A305374, A305393, A305394.
Cf. A293630.
Sequence in context: A309059 A368712 A293630 * A259154 A369933 A374327
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 23 2018
STATUS
approved