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 A005048 Minimal span of set of n elements with no 4-term arithmetic progression. 3

%I

%S 4,5,7,8,9,12,14,16,18,20,22,24,26,27,29,32,33,36,39,42,44,47,49,52,

%T 53,57,59,63,65,67,69,73,76,78,81,83,86,90,92,96,98,100,103,104,106,

%U 111,113,119,121,125,128,131,133,137,140

%N Minimal span of set of n elements with no 4-term arithmetic progression.

%C If the first appearance of n in A003003 is A003003(k) = n, then a(n) = k-1. - _Robert Israel_, Mar 21 2016

%H B. E. Brown and D. M. Gordon, <a href="http://dx.doi.org/10.1090/S0025-5718-96-00765-X">On sequences without geometric progressions</a>, Math. Comp. 65 (1996), no. 216, 1749-1754.

%H Sean A. Irvine, <a href="/A005048/a005048.out.txt">Example sets for a(4)-a(27)</a>

%e Example for n=13: { 1, 2, 3, 5, 6, 8, 9, 10, 16, 17, 18, 20, 21 } with span 20.

%Y Cf. A005047, A005049, A005050.

%K nonn,more

%O 4,1

%A _N. J. A. Sloane_

%E Corrected and extended by _David W. Wilson_, May 15 1997

%E a(22)-a(26) from _Sean A. Irvine_, Mar 17 2016

%E a(24)-a(26) corrected by _Robert Israel_, Mar 20 2016

%E a(27) from _Sean A. Irvine_, Mar 20 2016

%E a(28)-a(34) from _Robert Israel_, Mar 21 2016

%E a(35)-a(58) from _Fausto A. C. Cariboni_, Jun 17 2018

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Last modified April 23 14:15 EDT 2019. Contains 322386 sequences. (Running on oeis4.)