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A348485
Lexicographically earliest sequence of positive integers in which, for all positive k, there are exactly k contiguous pairs whose product is k, and a(k) * a(k+1) <> a(k+1) * a(k+2).
2
1, 1, 2, 2, 1, 3, 2, 2, 3, 1, 4, 2, 2, 3, 1, 5, 2, 3, 3, 2, 4, 3, 2, 4, 3, 3, 4, 2, 5, 1, 7, 2, 4, 3, 3, 4, 2, 5, 1, 7, 2, 4, 3, 3, 4, 2, 5, 1, 7, 2, 5, 1, 7, 2, 5, 3, 3, 4, 4, 3, 3, 4, 4, 3, 3, 4, 4, 5, 2, 7, 1, 9, 2, 5, 3, 3, 5, 2, 7, 1, 10, 2, 7, 1, 11, 2
OFFSET
1,3
COMMENTS
This sequence is a variant of A307720 where we don't allow consecutive equal products of contiguous pairs.
LINKS
EXAMPLE
The first terms, alongside a(n)*a(n+1), are:
n a(n) a(n)*a(n+1)
-- ---- -----------
1 1 1
2 1 2
3 2 4
4 2 2
5 1 3
6 3 6
7 2 4
8 2 6
9 3 3
10 1 4
11 4 8
12 2 4
13 2 6
14 3 3
15 1 5
PROG
(PARI) See Links section.
CROSSREFS
Cf. A307720, A348486 (the products).
Sequence in context: A348911 A039996 A039994 * A343188 A326394 A228425
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Oct 21 2021
STATUS
approved