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 A198685 Mixed palindromic van der Waerden numbers pdw(n,3;2)_2 ("unsatisfiable" part). 1
 3, 6, 9, 16, 21, 31, 44, 57, 77, 94, 113, 135, 155, 183, 205, 237, 279, 312, 347, 389, 405, 463, 507, 593, 607, 643, 699 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The smallest number M such that for all natural numbers m >= M there exists no partitioning of {1,...,m} into 2 parts such that the first part contains no arithmetic progression of length 3, and the second part contains no arithmetic progression of size n, and such that the partitioning is palindromic, that is, written as 0-1 string is a palindrome (reading the same from both sides). So pdw(1,3;2)_2=3 and pdw(2,3;2)_2=6. pdw(n,3;2) is a pair of natural numbers, where the first part (the "satisfiable part") is given by A198684. pdw(n,3;2) is the palindromic version of w(n,3;2) which is A007783. LINKS T. Ahmed and O. Kullmann and H. Snevily, On the van der Waerden numbers w(2;3,t) EXAMPLE pdw(3,3;2)_2=9, since ({2,4,5,7},{1,3,6,8}) is a palindromic partitioning of {1,...,8} such that no part contains an arithmetic progression of length 3, while there is no such a partitioning of {1,...,9} because of w(3,3;2)=9. CROSSREFS Cf. A007783. Sequence in context: A287554 A308777 A057855 * A070120 A070126 A127644 Adjacent sequences:  A198682 A198683 A198684 * A198686 A198687 A198688 KEYWORD hard,nonn AUTHOR Oliver Kullmann, Oct 28 2011 STATUS approved

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Last modified May 30 23:49 EDT 2020. Contains 334747 sequences. (Running on oeis4.)