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 A267301 Earliest positive increasing sequence having no 5-term subsequence with constant second differences. 8
 1, 2, 3, 4, 6, 7, 8, 9, 12, 14, 17, 20, 21, 23, 25, 31, 32, 37, 46, 47, 53, 56, 61, 63, 64, 67, 70, 72, 76, 87, 90, 93, 104, 112, 116, 120, 135, 138, 146, 153, 164, 177, 179, 180, 197, 201, 221, 224, 276, 277, 279, 282, 283, 285, 287, 295, 305, 317, 320, 327, 340, 354, 361, 364, 377, 380, 385, 391, 403, 415, 424, 430, 443 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS PROG (PARI) A267301(n, show=0, L=5, o=2, v=[1], 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. A267300 (nonnegative variant: starting with 0). 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. A240556 and A240557 for sequences avoiding 5-term subsequences with constant third differences. Sequence in context: A177500 A018772 A134003 * A233576 A128170 A018490 Adjacent sequences:  A267298 A267299 A267300 * A267302 A267303 A267304 KEYWORD nonn AUTHOR M. F. Hasler, Jan 12 2016 STATUS approved

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Last modified October 16 09:29 EDT 2019. Contains 328056 sequences. (Running on oeis4.)