cp's OEIS Frontend

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.

Showing 1-3 of 3 results.

A195663 Array read by antidiagonals: Consecutive finite permutations of positive integers in reverse colexicographic order.

Original entry on oeis.org

1, 2, 2, 3, 1, 1, 4, 3, 3, 3, 5, 4, 2, 1, 2, 6, 5, 4, 2, 3, 3, 7, 6, 5, 4, 1, 2, 1, 8, 7, 6, 5, 4, 1, 2, 2, 9, 8, 7, 6, 5, 4, 4, 1, 1, 10, 9, 8, 7, 6, 5, 3, 4, 4, 4, 11, 10, 9, 8, 7, 6, 5, 3, 2, 1, 2, 12, 11, 10, 9, 8, 7, 6, 5, 3, 2, 4, 4, 13, 12, 11, 10, 9, 8, 7, 6, 5, 3, 1, 2, 1, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 3, 1, 3, 3
Offset: 0

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Author

Tilman Piesk, Sep 22 2011

Keywords

Comments

Row n is the n-th finite permutation of {1,2,3,4,...}.

Examples

			The first 24 permutations of positive integers in rev colex order:
00  -->  1 2 3 4 5 6 7 8 ...
01  -->  2 1 3 4 ...
02  -->  1 3 2 4 ...
03  -->  3 1 2 4 ...
04  -->  2 3 1 4 ...
05  -->  3 2 1 4 ...
06  -->  1 2 4 3 ...
07  -->  2 1 4 3 ...
08  -->  1 4 2 3 ...
09  -->  4 1 2 3 ...
10  -->  2 4 1 3 ...
11  -->  4 2 1 3 ...
12  -->  1 3 4 2 ...
13  -->  3 1 4 2 ...
14  -->  1 4 3 2 ...
15  -->  4 1 3 2 ...
16  -->  3 4 1 2 ...
17  -->  4 3 1 2 ...
18  -->  2 3 4 1 ...
19  -->  3 2 4 1 ...
20  -->  2 4 3 1 ...
21  -->  4 2 3 1 ...
22  -->  3 4 2 1 ...
23  -->  4 3 2 1 ...
		

Crossrefs

Cf. A055089 (a very compact representation of these permutations).
Cf. A195664 (same for nonnegative integers, so all entries are smaller by 1).

Formula

a(n) = A195664(n)+1.

A055090 Number of cycles (excluding fixed points) of the n-th finite permutation in reversed colexicographic ordering (A055089).

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2
Offset: 0

Views

Author

Antti Karttunen, Apr 18 2000

Keywords

Comments

Among the first n! entries k appears A136394(n,k) times. - Tilman Piesk, Apr 06 2012

Crossrefs

Cf. A195663, A195664, A055089 (ordered finite permutations).
Cf. A198380 (cycle type of the n-th finite permutation).

Programs

  • Maple
    with(group); seq(nops(convert(PermRevLexUnrank(j),'disjcyc')),j=0..)];
    # Procedure PermRevLexUnrank given in A055089.

Formula

a(n) = A055093(n) - A055091(n).
a(n) = A056170(A290095(n)) = A060128(A060126(n)). - Antti Karttunen, Dec 30 2017

Extensions

Name changed by Tilman Piesk, Apr 06 2012

A198380 Cycle type of the n-th finite permutation represented by index number of A194602.

Original entry on oeis.org

0, 1, 1, 2, 2, 1, 1, 3, 2, 4, 4, 2, 2, 4, 1, 2, 3, 4, 4, 2, 2, 1, 4, 3, 1, 3, 3, 5, 5, 3, 2, 5, 4, 6, 6, 4, 4, 6, 2, 4, 5, 6, 6, 4, 4, 2, 6, 5, 2, 5, 4, 6, 6, 4, 1, 3, 2, 4, 4, 2, 3, 5, 4, 6, 6, 5, 5, 3, 6, 4, 5, 6, 4, 6, 2, 4, 5, 6, 2, 4, 1, 2, 3, 4, 4, 6
Offset: 0

Views

Author

Tilman Piesk, Oct 23 2011

Keywords

Comments

This sequence shows the cycle type of each finite permutation (A195663) as the index number of the corresponding partition. (When a permutation has a 3-cycle and a 2-cycle, this corresponds to the partition 3+2, etc.) Partitions can be ordered, so each partition can be denoted by its index in this order, e.g. 6 for the partition 3+2. Compare A194602.
From the properties of A194602 follows:
Entries 1,2,4,6,10,14,21... ( A000041(n)-1 from n=2 ) correspond to permutations with exactly one n-cycle (and no other cycles).
Entries 1,3,7,15,30,56,101... ( A000041(2n-1) from n=1 ) correspond to permutations with exactly n 2-cycles (and no other cycles), so these are the symmetric permutations.
Entries n = 1,3,4,7,9,10,12... ( A194602(n) has an even binary digit sum ) correspond to even permutations. This goes along with the fact, that a permutation is even when its partition contains an even number of even addends.
(Compare "Table for A194602" in section LINKS. Concerning the first two properties see especially the end of this file.)

Crossrefs

Cf. A195663, A195664, A055089 (ordered finite permutations).
Cf. A194602 (ordered partitions interpreted as binary numbers).
Cf. A181897 (number of n-permutations with cycle type k).

Extensions

Changed offset to 0 by Tilman Piesk, Jan 25 2012
Showing 1-3 of 3 results.