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A368795
Lexicographically earliest sequence of nonnegative integers such that the doubly-infinite symmetric sequence b defined by b(n) = b(-n) = a(n) for any n >= 0 has no three equidistant terms in arithmetic progression.
3
0, 1, 1, 2, 4, 2, 2, 1, 1, 4, 2, 4, 5, 5, 9, 3, 3, 5, 5, 10, 5, 4, 7, 3, 2, 8, 6, 2, 4, 2, 4, 7, 2, 3, 6, 5, 11, 1, 7, 15, 9, 6, 12, 10, 13, 10, 2, 13, 11, 8, 17, 9, 10, 13, 14, 1, 10, 11, 17, 15, 12, 1, 1, 5, 12, 11, 5, 6, 1, 17, 3, 15, 6, 6, 7, 6, 6, 17, 25
OFFSET
0,4
COMMENTS
This sequence is a variant of A229037 and A248625 with similar graphical features.
EXAMPLE
For n = 4:
- the first 4 terms of the sequence are: 0, 1, 1, 2,
- a(4) cannot equal 0 due to the progression b(-4) = 0, b(0) = 0, b(4) = 0,
- a(4) cannot equal 1 due to the progression b(-2) = 1, b(1) = 1, b(4) = 1,
- a(4) cannot equal 2 due to the progression b(0) = 0, b(2) = 1, b(4) = 2,
- a(4) cannot equal 3 due to the progression b(2) = 1, b(3) = 2, b(4) = 3,
- we chose a(4) = 4 as this does not induce arithmetic progressions.
PROG
(C++) See Links section.
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Rémy Sigrist, Jan 06 2024
STATUS
approved