cp's OEIS Frontend

A267307 Earliest positive increasing sequence having no 6-term subsequence with constant third differences.

%I A267307 #8 Jan 08 2021 06:56:08
%S A267307 1,2,3,4,5,7,8,9,10,12,13,14,15,29,30,32,33,34,35,36,38,39,41,48,80,
%T A267307 94,95,97,98,99,100,101,103,104,106,111,117,123,129,131,141,149,267,
%U A267307 282,297,304,305,307,309,312,314,319,325,327,328,329,331,332,333,338
%N A267307 Earliest positive increasing sequence having no 6-term subsequence with constant third differences.
%o A267307 (PARI) A267307(n, show=0, L=6, o=3, v=[1], D=v->v[2..-1]-v[1..-2])={ my(d, m); while( #v<n, show&&print1(v[#v]", "); v=concat(v, v[#v]); while( v[#v]++, forvec( i=vector(L, j, [if(j<L, j, #v), #v]), d=D(vecextract(v, i)); m=o; while(m--&&#Set(d=D(d))>1, ); #Set(d)>1||next(2), 2); break)); v[#v]} \\ _M. F. Hasler_, Jan 12 2016
%Y A267307 Cf. A267306 (nonnegative variant: starting with 0).
%Y A267307 No 3-term AP: A005836 (>=0), A003278 (>0);
%Y A267307 no 4-term AP: A240075 (>=0), A240555 (>0);
%Y A267307 no 5-term AP: A020654 (>=0), A020655 (>0);
%Y A267307 no 6-term AP: A020656 (>=0), A005838 (>0);
%Y A267307 no 7-term AP: A020657 (>=0), A020658 (>0);
%Y A267307 no 8-term AP: A020659 (>=0), A020660 (>0);
%Y A267307 no 9-term AP: A020661 (>=0), A020662 (>0);
%Y A267307 no 10-term AP: A020663 (>=0), A020664 (>0).
%Y A267307 Cf. A240075 and A240555 for sequences avoiding 4-term subsequences with constant second differences.
%Y A267307 Cf. A267300 and A267301 for sequences avoiding 5-term subsequences with constant second differences.
%Y A267307 Cf. A267302 and A267303 for sequences avoiding 6-term subsequences with constant second differences.
%Y A267307 Cf. A267304 and A267305 for sequences avoiding 7-term subsequences with constant second differences.
%Y A267307 Cf. A240556 and A240557 for sequences avoiding 5-term subsequences with constant third differences.
%K A267307 nonn
%O A267307 1,2
%A A267307 _M. F. Hasler_, Jan 12 2016
%E A267307 More terms from _Jinyuan Wang_, Jan 08 2021