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Decimal representation of permutations of lengths 1, 2, 3, ... arranged first by number of inversions and then lexicographically.
1

%I #26 Mar 27 2016 22:29:28

%S 1,12,21,123,132,213,231,312,321,1234,1243,1324,2134,1342,1423,2143,

%T 2314,3124,1432,2341,2413,3142,3214,4123,2431,3241,3412,4132,4213,

%U 3421,4231,4312,4321,12345,12354,12435,13245,21345,12453

%N Decimal representation of permutations of lengths 1, 2, 3, ... arranged first by number of inversions and then lexicographically.

%H David Consiglio, Jr., <a href="/A268532/b268532.txt">Table of n, a(n) for n = 1..5913</a>

%H David Consiglio, Jr., <a href="/A268532/a268532.py.txt">Python Program</a>

%e The 24 permutations of length 4 and their numbers of inversions:

%e 1234 0

%e 1243 1

%e 1324 1

%e 2134 1

%e 1342 2

%e 1423 2

%e 2143 2

%e 2314 2

%e 3124 2

%e 1432 3

%e 2341 3

%e 2413 3

%e 3142 3

%e 3214 3

%e 4123 3

%e 2431 4

%e 3241 4

%e 3412 4

%e 4132 4

%e 4213 4

%e 3421 5

%e 4231 5

%e 4312 5

%e 4321 6

%Y Cf. A000142 (n!), A030299 (in purely lexicographic order), A008302 (number of permutations with k inversions).

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_, Feb 19 2016