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 A191721 Permutations in S_n avoiding the patterns {4321, 34512, 45123, 35412, 43512, 45132, 45213, 53412, 45312, 45231} 0
 1, 2, 6, 23, 94, 391, 1633, 6827, 28548, 119384, 499255, 2087854, 8731285, 36513737, 152698377, 638575958, 2670488470, 11167831459, 46703238346, 195310296371, 816776592369, 3415713427499, 14284320005992, 59736216859096 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A(n) is also the number of w in S_n for which the number of repeated letters in a reduced decomposition of w equals the number of 321- and 3412-patterns in w. The generating function can be automatically computed by the Maple package INSENC listed in the links. - Vincent Vatter, Jun 16 2011 LINKS B. E. Tenner, Repetition in reduced decompositions, arXiv:1106.2839 [math.CO] V. Vatter, Maple package INSENC FORMULA G.f.: (1-4*x+x^3)/((1-x) * (1-4*x-x^2+x^3)). - Vincent Vatter, Jun 16 2011 EXAMPLE A(4)=23 because all permutations in S_4 except 4321 avoid these patterns.  Also, all permutations in S_4 except 4321 have repeated letters equaling the number of 321- and 3412-patterns.  (Note that 4321 has 3 repeated letters, but 4 of these patterns.) CROSSREFS Sequence in context: A150290 A150291 A150292 * A150293 A150294 A150295 Adjacent sequences:  A191718 A191719 A191720 * A191722 A191723 A191724 KEYWORD nonn AUTHOR Bridget Tenner, Jun 13 2011 STATUS approved

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Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)