A293866 - OEIS

A293866

For n > 2: when computing A229037(n), there are up to floor((n-1)/2) forbidden values (i.e. values that would lead to an arithmetic progression); a(n) = greatest forbidden value when computing A229037(n).

1, 3, 3, 1, 3, 3, 6, 6, 7, 7, 7, 7, 7, 7, 7, 6, 6, 7, 7, 7, 7, 7, 11, 11, 12, 13, 14, 12, 13, 14, 14, 15, 16, 14, 15, 16, 16, 17, 17, 16, 17, 17, 14, 15, 16, 16, 17, 17, 16, 17, 17, 12, 13, 14, 13, 13, 14, 14, 15, 16, 16, 16, 16, 18, 17, 24, 17, 21, 21, 18, 21

(list; graph; refs; listen; history; text; internal format)

OFFSET

3,2

COMMENTS

The scatterplot of this sequence has interesting features, such as rectangular clusters of points.

For any n > 2, A229037(n) <= a(n) + 1, with equality for n=3, 6, 8, 24 (and possibly no other values).

LINKS

Rémy Sigrist, Table of n, a(n) for n = 3..10000

Rémy Sigrist, Scatterplot of the first 100000 terms

Rémy Sigrist, C++ program for A293866

FORMULA

a(n) = max_{j=1..floor((n-1)/2)} (2*A229037(n-j) - A229037(n-2*j)).