This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A056019 Self-inverse infinite permutation which shows the position of each finite permutation's inverse permutation in A055089. 13
 0, 1, 2, 4, 3, 5, 6, 7, 12, 18, 13, 19, 8, 10, 14, 20, 16, 22, 9, 11, 15, 21, 17, 23, 24, 25, 26, 28, 27, 29, 48, 49, 72, 96, 73, 97, 50, 52, 74, 98, 76, 100, 51, 53, 75, 99, 77, 101, 30, 31, 36, 42, 37, 43, 54, 55, 78, 102, 79, 103, 60, 66, 84, 108, 90, 114, 61, 67, 85 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS PermRevLexRank and PermRevLexUnrank have been modified from the algorithms PermLexRank and PermLexUnrank presented in the book "Combinatorial Algorithms, Generation, Enumeration and Search", by Donald L. Kreher and Douglas R. Stinson. LINKS Tilman Piesk, Table of n, a(n) for n = 0..5039 FORMULA [seq(PermRevLexRank(convert(invperm(convert(PermRevLexUnrank(j), 'disjcyc')), 'permlist', nops(PermRevLexUnrank(j)))), j=0..200)]; EXAMPLE E.g. the permutation [2,3,1] is the 4th permutation (counting from 0th, the identity permutation) of A055089, its inverse permutation is [3,1,2] which is 3rd, thus a(4)=3 and a(3)=4. MAPLE PermRevLexRank := proc(pp) local p, n, i, j, r; p := pp; n := nops(p); r := 0; for j from n by -1 to 1 do r := r + (((j-p[j])*((j-1)!))); for i from 1 to (j-1) do if(p[i] > p[j]) then p[i] := p[i]-1; fi; od; od; RETURN(r); end; MATHEMATICA A056019 = Position[Ordering /@ #, #[[#2]]][[1, 1]] - 1 &[Reverse@SortBy[Permutations@Range@Ceiling@InverseFunction[Factorial][# + 1], Reverse], # + 1] &; Array[A056019, 69, 0] (* JungHwan Min, Oct 10 2016 *) A056019L = Ordering[Ordering /@ Permutations@Range@Ceiling@InverseFunction[Factorial][# + 1]] - 1 &; A056019L (* JungHwan Min, Oct 10 2016 *) CROSSREFS Sequence in context: A131042 A274631 A275335 * A125963 A111269 A275657 Adjacent sequences:  A056016 A056017 A056018 * A056020 A056021 A056022 KEYWORD nonn AUTHOR Antti Karttunen, Jun 08 2000 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 16 13:32 EDT 2019. Contains 328093 sequences. (Running on oeis4.)