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A055091
Minimum number of transpositions needed to represent each permutation given in reversed colexicographic ordering A055089.
9
0, 1, 1, 2, 2, 1, 1, 2, 2, 3, 3, 2, 2, 3, 1, 2, 2, 3, 3, 2, 2, 1, 3, 2, 1, 2, 2, 3, 3, 2, 2, 3, 3, 4, 4, 3, 3, 4, 2, 3, 3, 4, 4, 3, 3, 2, 4, 3, 2, 3, 3, 4, 4, 3, 1, 2, 2, 3, 3, 2, 2, 3, 3, 4, 4, 3, 3, 2, 4, 3, 3, 4, 3, 4, 2, 3, 3, 4, 2, 3, 1, 2, 2, 3, 3, 4, 2, 3, 3, 4, 4, 3, 3, 4, 2, 3, 4, 3, 3, 2, 4, 3, 3, 2, 2
OFFSET
0,4
FORMULA
a(n) = A055093(n) - A055090(n).
a(n) = A046660(A290095(n)) = A060130(A060126(n)). - Antti Karttunen, Dec 30 2017
MAPLE
with(group); [seq(count_transpositions(convert(PermRevLexUnrank(j), 'disjcyc')), j=0..)];
count_transpositions := proc(l) local c, t; t := 0; for c in l do t := t + (nops(c)-1); od; RETURN(t); end;
# Procedure PermRevLexUnrank given in A055089.
CROSSREFS
Cf. also A034968 (minimum number of adjacent transpositions).
Sequence in context: A318439 A106180 A274369 * A332380 A014678 A332381
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 18 2000
EXTENSIONS
Entry revised by Antti Karttunen, Dec 30 2017
STATUS
approved