This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A055091 #15 Dec 30 2017 10:00:29 %S A055091 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, %T A055091 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, %U A055091 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 %N A055091 Minimum number of transpositions needed to represent each permutation given in reversed colexicographic ordering A055089. %H A055091 Antti Karttunen, <a href="/A055091/b055091.txt">Table of n, a(n) for n = 0..40320</a> %H A055091 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a> %F A055091 a(n) = A055093(n) - A055090(n). %F A055091 a(n) = A046660(A290095(n)) = A060130(A060126(n)). - _Antti Karttunen_, Dec 30 2017 %p A055091 with(group); [seq(count_transpositions(convert(PermRevLexUnrank(j),'disjcyc')),j=0..)]; %p A055091 count_transpositions := proc(l) local c,t; t := 0; for c in l do t := t + (nops(c)-1); od; RETURN(t); end; %p A055091 # Procedure PermRevLexUnrank given in A055089. %Y A055091 Cf. A046660, A055089, A055090, A055093, A060130, A290095. %Y A055091 Cf. also A034968 (minimum number of adjacent transpositions). %K A055091 nonn %O A055091 0,4 %A A055091 _Antti Karttunen_, Apr 18 2000 %E A055091 Entry revised by _Antti Karttunen_, Dec 30 2017