A330623 Lexicographically earliest sequence of positive terms such that for any n > 0 and k > 0, a(n+2*k) <> gcd(a(n), a(n+k)).

1, 1, 2, 2, 3, 2, 2, 3, 3, 4, 4, 2, 4, 3, 3, 5, 3, 3, 4, 4, 5, 4, 4, 2, 5, 6, 2, 5, 6, 3, 6, 4, 3, 6, 6, 5, 4, 4, 3, 4, 5, 5, 6, 7, 5, 4, 4, 6, 4, 4, 7, 5, 5, 6, 5, 6, 7, 8, 4, 5, 7, 7, 6, 7, 8, 6, 3, 6, 7, 8, 5, 5, 8, 3, 6, 9, 5, 8, 7, 5, 9, 7, 7, 8, 6, 5, 8

Offset: 1

Author

Rémy Sigrist, Dec 21 2019

Keywords

• nonn

Comments

This sequence differs radically from the variant where we consider nonnegative terms (A330622).

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, Scatterplot of the first 250000 terms
• Rémy Sigrist, C program for A330623

Crossrefs

Cf. A330622 (nonnegative variant).

See A330267 for similar sequences.

Programs

C

See Links section.