cp's OEIS Frontend

A333866 Lexicographically earliest sequence of distinct positive integers, which when mapped onto a square spiral, gives a set without four distinct points forming a square.

%I A333866 #14 Apr 12 2020 13:58:23
%S A333866 1,2,3,5,6,7,10,11,13,14,17,18,20,21,26,27,30,31,37,38,41,43,44,46,50,
%T A333866 52,55,57,58,65,66,70,73,79,82,83,88,91,92,101,102,104,110,111,116,
%U A333866 122,124,127,132,133,141,143,145,146,152,156,157,167,170,171,180
%N A333866 Lexicographically earliest sequence of distinct positive integers, which when mapped onto a square spiral, gives a set without four distinct points forming a square.
%C A333866 This sequence has similarities with A005282.
%H A333866 Rémy Sigrist, <a href="/A333866/b333866.txt">Table of n, a(n) for n = 1..10000</a>
%H A333866 Rémy Sigrist, <a href="/A333866/a333866.png">Scatterplot of (A174344(a(n)), A274923(a(n))) in the region -2000 <= x, y <= 2000</a>
%H A333866 Rémy Sigrist, <a href="/A333866/a333866.txt">C# program for A333866</a>
%e A333866 The first terms, mapped onto a square spiral, are:
%e A333866         65---*---*---*---*---*---*--58--57
%e A333866          |                               |
%e A333866         66  37---*---*---*---*---*--31   *
%e A333866          |   |                       |   |
%e A333866          *  38  17---*---*--14--13  30  55
%e A333866          |   |   |               |   |   |
%e A333866          *   *  18   5---*---3   *   *   * <-- As the sequence contains 2, 13
%e A333866          |   |   |   |       |   |   |   |     and 27, it cannot contain 54.
%e A333866          *   *   *   6   1---2  11   *   *
%e A333866          |   |   |   |           |   |   |
%e A333866         70  41  20   7---*---*--10  27  52
%e A333866          |   |   |                   |   |
%e A333866          *   *  21---*---*---*---*--26   *
%e A333866          |   |                           |
%e A333866          *  43--44---*--46---*---*---*--50
%e A333866          |
%e A333866         73---*---*---*---*---*--79---*---*
%o A333866 (C#) See Links section.
%Y A333866 See A333825 for a similar sequences.
%Y A333866 Cf. A005282, A174344, A274923.
%K A333866 nonn
%O A333866 1,2
%A A333866 _Rémy Sigrist_, Apr 08 2020