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A036585 Ternary Thue-Morse sequence: closed under a->abc, b->ac, c->b. 9
3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 3, 1, 3, 2, 1, 3, 1, 2, 3, 1, 3, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 3, 1, 3, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 1, 3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 3, 1, 3, 2, 1, 3, 1, 2, 3, 1, 3, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 1, 3, 2, 1, 3, 1, 2, 3, 2, 1, 2, 3, 1, 3, 2, 1, 2, 3, 2, 1, 3, 1, 2, 3, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
First differences of A001969. Observed by Franklin T. Adams-Watters, proved by Max Alekseyev, Aug 30 2006
REFERENCES
M. Lothaire, Combinatorics on Words. Addison-Wesley, Reading, MA, 1983, p. 26.
LINKS
FORMULA
a(n) = A001969(n+1) - A001969(n). - Franklin T. Adams-Watters, Aug 28 2006
a(n) = A029883(n) + 2 = A036577(n) + 1.
PROG
(PARI) a(n)=if(n<1 || valuation(n, 2)%2, 2, 2-(-1)^subst(Pol(binary(n)), x, 1))
(Haskell)
a036585 n = a036585_list !! (n-1)
a036585_list = 3 : concat (map f a036585_list)
where f 1 = [1, 2, 3]; f 2 = [1, 3]; f 3 = [2]
-- Reinhard Zumkeller, Oct 31 2012
def A036585(n): return 2+(n.bit_count()&1)-((n-1).bit_count()&1) # Chai Wah Wu, Mar 03 2023
CROSSREFS
Sequence in context: A237881 A112745 A205564 * A260454 A164848 A213514
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified June 17 02:48 EDT 2024. Contains 373432 sequences. (Running on oeis4.)