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 A267304 Earliest nonnegative increasing sequence having no 7-term subsequence with constant second differences. 4
 0, 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 24, 26, 28, 29, 31, 33, 35, 38, 40, 41, 43, 49, 50, 52, 53, 58, 59, 62, 63, 64, 69, 70, 72, 73, 77, 81, 82 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS PROG (PARI) A267304(n, show=0, L=7, o=2, v=[0], D=v->v[2..-1]-v[1..-2])={ my(d, m); while( #v1, ); #Set(d)>1||next(2), 2); break)); v[#v]} \\ M. F. Hasler, Jan 12 2016 CROSSREFS Cf. A267305 (positive variant: starting with 1). No 3-term AP: A005836 (>=0), A003278 (>0); no 4-term AP: A240075 (>=0), A240555 (>0); no 5-term AP: A020654 (>=0), A020655 (>0); no 6-term AP: A020656 (>=0), A005838 (>0); no 7-term AP: A020657 (>=0), A020658 (>0); no 8-term AP: A020659 (>=0), A020660 (>0); no 9-term AP: A020661 (>=0), A020662 (>0); no 10-term AP: A020663 (>=0), A020664 (>0). Cf. A240075 and A240555 for sequences avoiding 4-term subsequences with constant second differences. Cf. A267300 and A267301 for sequences avoiding 5-term subsequences with constant second differences. Cf. A267302 and A267303 for sequences avoiding 6-term subsequences with constant second differences. Cf. A240556 and A240557 for sequences avoiding 5-term subsequences with constant third differences. Sequence in context: A057907 A109234 A335137 * A002855 A303234 A175233 Adjacent sequences:  A267301 A267302 A267303 * A267305 A267306 A267307 KEYWORD nonn,more AUTHOR M. F. Hasler, Jan 12 2016 STATUS approved

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Last modified June 2 14:21 EDT 2020. Contains 334787 sequences. (Running on oeis4.)