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 A225745 Smallest k such that n numbers can be picked in {1,...,k} with no four in arithmetic progression. 2
 1, 2, 3, 5, 6, 8, 9, 10, 13, 15, 17, 19, 21, 23, 25, 27, 28, 30, 33, 34, 37, 40, 43, 45, 48, 50, 53, 54, 58, 60, 64, 66, 68, 70, 74, 77 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES Knuth, Donald E., Satisfiability,  Fascicle 6, volume 4 of The Art of Computer Programming. Addison-Wesley, 2015, pages 135 and 190, Problem 31. LINKS Samuel S. Wagstaff, Jr., On k-free sequences of integers, Math. Comp., 26 (1972), 767-771. EXAMPLE a(8)=10 because of the unique solution 1 2 3 5 6 8 9 10. CROSSREFS This sequence is to A003003 as A065825 is to A003002. Sequence in context: A288373 A087067 A166018 * A238896 A190842 A273106 Adjacent sequences:  A225742 A225743 A225744 * A225746 A225747 A225748 KEYWORD nonn,more AUTHOR Don Knuth, Aug 05 2013 STATUS approved

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Last modified August 17 06:56 EDT 2018. Contains 313810 sequences. (Running on oeis4.)