A337005 Leech's order 13 uniform cyclic squarefree word.
0, 1, 2, 1, 0, 2, 1, 2, 0, 1, 2, 1, 0, 1, 2, 0, 2, 1, 0, 2, 0, 1, 2, 0, 2, 1, 2, 0, 1, 0, 2, 1, 0, 1, 2, 0, 1, 0, 2, 1, 2, 0, 2, 1, 0, 2, 0, 1, 2, 0, 2, 1, 0, 1, 2, 1, 0, 2, 1, 2, 0, 1, 2, 1, 0, 2, 0, 1, 0, 2, 1, 0, 1, 2, 0, 1, 0, 2, 1, 2, 0, 2, 1, 0, 2, 0, 1
Offset: 0
Links
- Kevin Ryde, Table of n, a(n) for n = 0..6590
- Rob Burns, Synchronisation of running sums of automatic sequences, arXiv:2405.17536 [math.NT], 2024. See p. 13.
- John Leech, A Problem on Strings of Beads, The Mathematical Gazette, volume 41, number 338, December 1957, item 2726, pages 277-278.
- Boris Zolotov, Another Solution to the Thue Problem of Non-Repeating Words, arXiv:1505.00019 [math.CO], 2015. (Section 2 morphism 3, then section 5 result 8 and proofs in section 9.)
- Index entries for sequences that are fixed points of mappings
- Index entries for sequences related to squarefree words
Crossrefs
Cf. A170823.
Programs
-
PARI
my(table=[0,1,2,1,0,2,1,2,0,1,2,1,0]); a(n) = my(v=digits(n,#table)); sum(i=1,#v, table[v[i]+1])%3;
Formula
Fixed point of the morphism, starting from 0,
0 -> 0,1,2,1,0,2,1,2,0,1,2,1,0 [Leech]
1 -> 1,2,0,2,1,0,2,0,1,2,0,2,1
2 -> 2,0,1,0,2,1,0,1,2,0,1,0,2
a(n) = (Sum_{d each base 13 digit of n} t(d)) mod 3, where t(d) = 0,1,2,1,0,2,1,2,0,1,2,1,0 according as d=0 to 12 respectively.
Comments