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A005837 Sequence contains no 4-term 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 (list; graph; refs; listen; history; text; internal format)
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), 1353-1359.

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 3-term starting at 0), A003278 (no 3-term 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

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Last modified July 31 17:29 EDT 2014. Contains 245085 sequences.