login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A005839 Lexicographically earliest increasing nonnegative sequence that contains no 4-term arithmetic progression.
(Formerly M0956)
19
0, 1, 2, 4, 5, 7, 8, 9, 14, 15, 16, 18, 25, 26, 28, 29, 30, 33, 36, 48, 49, 50, 52, 53, 55, 56, 57, 62, 64, 65, 66, 79, 86, 87, 88, 90, 93, 98, 101, 104, 105, 108, 109, 110, 121, 125, 135, 144, 148, 150, 151, 159, 162, 166, 168, 169, 170, 173, 175, 176, 182 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n) = A005837(n) - 1. - Alois P. Heinz, Jan 31 2014

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, E10.

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

LINKS

David W. Wilson, Table of n, a(n) for n = 1..10000 a(1..1001) from Alois P. Heinz

MATHEMATICA

t = {0, 1, 2}; Do[s = Table[Append[i, n], {i, Subsets[t, {3}]}];

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

CROSSREFS

Summary of increasing sequences avoiding arithmetic progressions of specified lengths (the second of each pair is obtained by adding 1 to the first):

3-term AP: A005836 (>=0), A003278 (>0);

4-term AP: A005839 (>=0), A005837 (>0);

5-term AP: A020654 (>=0), A020655 (>0);

6-term AP: A020656 (>=0), A005838 (>0);

7-term AP: A020657 (>=0), A020658 (>0);

8-term AP: A020659 (>=0), A020660 (>0);

9-term AP: A020661 (>=0), A020662 (>0);

10-term AP: A020663 (>=0), A020664 (>0).

Sequence in context: A219640 A184164 A190852 * A254792 A062102 A092289

Adjacent sequences:  A005836 A005837 A005838 * A005840 A005841 A005842

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Jeffrey Shallit, Aug 15 1995.

Edited (with new offset, etc.) by N. J. A. Sloane, Jan 04 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 12:00 EDT 2018. Contains 316263 sequences. (Running on oeis4.)