

A005837


Sequence contains no 4term arithmetic progression.
(Formerly M0621)


3



1, 2, 3, 5, 6, 8, 9, 10, 15, 16, 17, 19, 26, 27, 29, 30, 31, 34, 37, 49, 50, 51, 53, 54, 56, 57, 58, 63, 65, 66, 67, 80, 87, 88, 89, 91, 94, 99, 102, 105, 106, 109, 110, 111, 122, 126, 136, 145, 149, 151, 152, 160, 163, 167, 169, 170, 171, 174, 176, 177, 183, 187, 188, 194, 196
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OFFSET

0,2


COMMENTS

a(n) = A005839(n) + 1.  Alois P. Heinz, Jan 31 2014


REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000
J. L. Gerver and L. T. Ramsey, Sets of integers with no long arithmetic progressions generated by the greedy algorithm, Math. Comp., 33 (1979), 13531359.


MATHEMATICA

t = {1, 2, 3}; Do[s = Table[Append[i, n], {i, Subsets[t, {3}]}]; If[! MemberQ[Table[Differences[i, 2], {i, s}], {0, 0}], AppendTo[t, n]], {n, 4, 200}]; t (* T. D. Noe, Apr 17 2014 *)


CROSSREFS

Cf. A005836 (no 3term starting at 0), A003278 (no 3term starting at 1).
Sequence in context: A238896 A190842 A191179 * A214980 A098161 A026194
Adjacent sequences: A005834 A005835 A005836 * A005838 A005839 A005840


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Jeffrey Shallit


STATUS

approved



