A330622 Lexicographically earliest sequence of nonnegative terms such that for any n > 0 and k > 0, a(n+2*k) <> gcd(a(n), a(n+k)).

0, 0, 1, 0, 0, 1, 2, 2, 3, 0, 0, 3, 0, 0, 4, 2, 5, 3, 5, 6, 3, 4, 4, 6, 6, 5, 4, 0, 0, 7, 0, 0, 7, 8, 8, 9, 0, 0, 7, 0, 0, 3, 8, 5, 3, 5, 9, 9, 5, 8, 7, 9, 2, 7, 10, 4, 3, 10, 6, 7, 6, 10, 10, 6, 6, 4, 10, 4, 9, 6, 11, 6, 6, 8, 11, 5, 8, 8, 4, 10, 11, 0, 0, 7

Offset: 1

Author

Rémy Sigrist, Dec 21 2019

Keywords

• nonn

Comments

This sequence differs radically from the variant where we consider only positive terms (A330623).

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 A330622

Crossrefs

Cf. A003278 (positions of 0's), A330623 (positive variant).

See A330267 for similar sequences.

Programs

C

See Links section.

Formula

a(n) = 0 iff n belongs to A003278.