A248639 Least nonnegative sequence which does not contain a 4-term equidistant subsequence (a(n+k*d); k=0,1,2,3) in arithmetic progression.

0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 1, 2, 0, 0, 0, 1, 0, 1, 1, 1, 2, 2, 2, 0, 0, 2, 0, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 2, 2, 1, 2, 1, 2, 2, 4, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 1, 1, 1, 2, 0, 1, 0, 0, 0, 1, 1, 1, 2, 3, 1, 2, 1, 1, 1, 2, 2, 0, 2, 2, 2, 4, 4, 3, 0, 0, 0, 2, 0, 1, 2, 0, 4, 2, 1, 5, 0, 2, 1, 1, 2, 1, 0, 0, 2, 2, 0, 0, 0, 3, 0, 0, 1, 1, 1, 4, 1, 2, 3, 0, 1, 2, 1, 0, 3, 3, 4, 1, 1, 3

Offset: 0

Author

M. F. Hasler, Oct 10 2014

Keywords

• nonn

Comments

See A248625 for more information, links and examples.

See A248641 for the "positive integers" variant.

Crossrefs

Cf. A248625, A248640, A248641, A248627, A229037, A241752.

Programs

PARI

a=[];for(n=1,190,a=concat(a,0);while(hasAP(a,4),a[#a]++));a \\ See A248625 for hasAP().