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 A207018 Number of permutations in S_n with major index equal to inversion number. 1
 1, 2, 4, 10, 28, 116, 576, 3634, 26620, 223440, 2100964, 21888712, 250062982, 3108430640 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS At first equal to and eventually greater than corresponding entry of A195924, number of fixed points of Foata's bijection. For any large n, the two permutations with maj and inv both 2 are 2314..n, and 14235..n. LINKS Joerg Arndt, C++ program to compute terms. EXAMPLE A(4)=10: the 10 permutations of 4 elements with major index equal to inversion number are    #:       perm      #inv.   inversion table    1:    [ 0 1 2 3 ]   0    [ 0 0 0 ]    2:    [ 0 3 1 2 ]   2    [ 0 2 0 ]    3:    [ 1 0 2 3 ]   1    [ 0 0 1 ]    4:    [ 1 2 0 3 ]   2    [ 0 1 1 ]    5:    [ 1 2 3 0 ]   3    [ 1 1 1 ]    6:    [ 2 1 0 3 ]   3    [ 0 1 2 ]    7:    [ 2 1 3 0 ]   4    [ 1 1 2 ]    8:    [ 2 3 1 0 ]   5    [ 1 2 2 ]    9:    [ 3 0 2 1 ]   4    [ 1 0 3 ]   10:    [ 3 2 1 0 ]   6    [ 1 2 3 ] CROSSREFS Cf. A195924. Sequence in context: A085549 A022492 A123429 * A006841 A003223 A061417 Adjacent sequences:  A207015 A207016 A207017 * A207019 A207020 A207021 KEYWORD nonn,hard,more AUTHOR William J. Keith, Feb 14 2012 EXTENSIONS a(14) by Joerg Arndt, Sep 29 2012. STATUS approved

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Last modified November 18 17:56 EST 2017. Contains 294894 sequences.