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 1-6 of 6 results.

A066099 Triangle read by rows, in which row n lists the compositions of n in reverse lexicographic order.

Original entry on oeis.org

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

Views

Author

Alford Arnold, Dec 30 2001

Keywords

Comments

The representation of the compositions (for fixed n) is as lists of parts, the order between individual compositions (for the same n) is (list-)reversed lexicographic; see the example by Omar E. Pol. - Joerg Arndt, Sep 03 2013
This is the standard ordering for compositions in this database; it is similar to the Mathematica ordering for partitions (A080577). Other composition orderings include A124734 (similar to the Abramowitz & Stegun ordering for partitions, A036036), A108244 (similar to the Maple partition ordering, A080576), etc (see crossrefs).
Factorize each term in A057335; sequence records the values of the resulting exponents. It also runs through all possible permutations of multiset digits.
This can be regarded as a table in two ways: with each composition as a row, or with the compositions of each integer as a row. The first way has A000120 as row lengths and A070939 as row sums; the second has A001792 as row lengths and A001788 as row sums. - Franklin T. Adams-Watters, Nov 06 2006
This sequence includes every finite sequence of positive integers. - Franklin T. Adams-Watters, Nov 06 2006
Compositions (or ordered partitions) are also generated in sequence A101211. - Alford Arnold, Dec 12 2006
The equivalent sequence for partitions is A228531. - Omar E. Pol, Sep 03 2013
The sole partition of zero has no components, not a single component of length one. Hence the first nonempty row is row 1. - Franklin T. Adams-Watters, Apr 02 2014 [Edited by Andrey Zabolotskiy, May 19 2018]
See sequence A261300 for another version where the terms of each composition are concatenated to form one single integer: (0, 1, 2, 11, 3, 21, 12, 111,...). This also shows how the terms can be obtained from the binary numbers A007088, cf. Arnold's first Example. - M. F. Hasler, Aug 29 2015
The k-th composition in the list is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This is described as the standard ordering used in the OEIS, although the sister sequence A228351 is also sometimes considered to be canonical. Both sequences define a bijective correspondence between nonnegative integers and integer compositions. - Gus Wiseman, May 19 2020
First differences of A030303 = positions of bits 1 in the concatenation A030190 (= A030302) of numbers written in binary (A007088). - Indices of record values (= first occurrence of n) are given by A005183: a(A005183(n)) = n, cf. FORMULA for more. - M. F. Hasler, Oct 12 2020
The geometric mean approaches the Somos constant (A112302). - Jwalin Bhatt, Feb 10 2025

Examples

			A057335 begins 1 2 4 6 8 12 18 30 16 24 36 ... so we can write
  1 2 1 3 2 1 1 4 3 2 2 1 1 1 1 ...
  . . 1 . 1 2 1 . 1 2 1 3 2 1 1 ...
  . . . . . . 1 . . . 1 . 1 2 1 ...
  . . . . . . . . . . . . . . 1 ...
and the columns here gives the rows of the triangle, which begins
  1
  2; 1 1
  3; 2 1; 1 2; 1 1 1
  4; 3 1; 2 2; 2 1 1; 1 3; 1 2 1; 1 1 2; 1 1 1 1
  ...
From _Omar E. Pol_, Sep 03 2013: (Start)
Illustration of initial terms:
  -----------------------------------
  n  j       Diagram   Composition j
  -----------------------------------
  .               _
  1  1           |_|   1;
  .             _ _
  2  1         |  _|   2,
  2  2         |_|_|   1, 1;
  .           _ _ _
  3  1       |    _|   3,
  3  2       |  _|_|   2, 1,
  3  3       | |  _|   1, 2,
  3  4       |_|_|_|   1, 1, 1;
  .         _ _ _ _
  4  1     |      _|   4,
  4  2     |    _|_|   3, 1,
  4  3     |   |  _|   2, 2,
  4  4     |  _|_|_|   2, 1, 1,
  4  5     | |    _|   1, 3,
  4  6     | |  _|_|   1, 2, 1,
  4  7     | | |  _|   1, 1, 2,
  4  8     |_|_|_|_|   1, 1, 1, 1;
(End)
		

Crossrefs

Lists of compositions of integers: this sequence (reverse lexicographic order; minus one gives A108730), A228351 (reverse colexicographic order - every composition is reversed; minus one gives A163510), A228369 (lexicographic), A228525 (colexicographic), A124734 (length, then lexicographic; minus one gives A124735), A296774 (length, then reverse lexicographic), A337243 (length, then colexicographic), A337259 (length, then reverse colexicographic), A296773 (decreasing length, then lexicographic), A296772 (decreasing length, then reverse lexicographic), A337260 (decreasing length, then colexicographic), A108244 (decreasing length, then reverse colexicographic), also A101211 and A227736 (run lengths of bits).
Cf. row length and row sums for different splittings into rows: A000120, A070939, A001792, A001788.
Cf. lists of partitions of integers, or multisets of integers: A026791 and crosserfs therein, A112798 and crossrefs therein.
See link for additional crossrefs pertaining to standard compositions.
A related ranking of finite sets is A048793/A272020.

Programs

  • Haskell
    a066099 = (!!) a066099_list
    a066099_list = concat a066099_tabf
    a066099_tabf = map a066099_row [1..]
    a066099_row n = reverse $ a228351_row n
    -- (each composition as a row)
    -- Peter Kagey, Aug 25 2016
    
  • Mathematica
    Table[FactorInteger[Apply[Times, Map[Prime, Accumulate @ IntegerDigits[n, 2]]]][[All, -1]], {n, 41}] // Flatten (* Michael De Vlieger, Jul 11 2017 *)
    stc[n_] := Differences[Prepend[Join @@ Position[Reverse[IntegerDigits[n, 2]], 1], 0]] // Reverse;
    Table[stc[n], {n, 0, 20}] // Flatten (* Gus Wiseman, May 19 2020 *)
    Table[Reverse @ LexicographicSort @ Flatten[Permutations /@ Partitions[n], 1], {n, 10}] // Flatten (* Eric W. Weisstein, Jun 26 2023 *)
  • PARI
    arow(n) = {local(v=vector(n),j=0,k=0);
       while(n>0,k++; if(n%2==1,v[j++]=k;k=0);n\=2);
       vector(j,i,v[j-i+1])} \\ returns empty for n=0. - Franklin T. Adams-Watters, Apr 02 2014
    
  • Python
    from itertools import islice
    from itertools import accumulate, count, groupby, islice
    def A066099_gen():
        for i in count(1):
            yield [len(list(g)) for _,g in groupby(accumulate(int(b) for b in bin(i)[2:]))]
    A066099 = list(islice(A066099_gen(), 120))  # Jwalin Bhatt, Feb 28 2025
  • Sage
    def a_row(n): return list(reversed(Compositions(n)))
    flatten([a_row(n) for n in range(1,6)]) # Peter Luschny, May 19 2018
    

Formula

From M. F. Hasler, Oct 12 2020: (Start)
a(n) = A030303(n+1) - A030303(n).
a(A005183(n)) = n; a(A005183(n)+1) = n-1 (n>1); a(A005183(n)+2) = 1. (End)

Extensions

Edited with additional terms by Franklin T. Adams-Watters, Nov 06 2006
0th row removed by Andrey Zabolotskiy, May 19 2018

A296774 Triangle read by rows in which row n lists the compositions of n ordered first by length and then reverse-lexicographically.

Original entry on oeis.org

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

Views

Author

Gus Wiseman, Dec 20 2017

Keywords

Examples

			Triangle of compositions begins:
(1),
(2),(11),
(3),(21),(12),(111),
(4),(31),(22),(13),(211),(121),(112),(1111),
(5),(41),(32),(23),(14),(311),(221),(212),(131),(122),(113),(2111),(1211),(1121),(1112),(11111).
		

Crossrefs

Programs

  • Mathematica
    Table[Sort[Join@@Permutations/@IntegerPartitions[n],Or[Length[#1]
    				

A296772 Triangle read by rows in which row n lists the compositions of n ordered first by decreasing length and then reverse-lexicographically.

Original entry on oeis.org

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

Views

Author

Gus Wiseman, Dec 20 2017

Keywords

Comments

The ordering of compositions in each row is consistent with the reverse-Mathematica ordering of expressions (cf. A124734).
Length of k-th composition is A124748(k-1)+1. - Andrey Zabolotskiy, Dec 20 2017

Examples

			Triangle of compositions begins:
(1),
(11),(2),
(111),(21),(12),(3),
(1111),(211),(121),(112),(31),(22),(13),(4),
(11111),(2111),(1211),(1121),(1112),(311),(221),(212),(131),(122),(113),(41),(32),(23),(14),(5).
		

Crossrefs

Programs

  • Mathematica
    Table[Reverse[Sort[Join@@Permutations/@IntegerPartitions[n]]],{n,6}]

A296773 Triangle read by rows in which row n lists the compositions of n ordered first by decreasing length and then lexicographically.

Original entry on oeis.org

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

Views

Author

Gus Wiseman, Dec 20 2017

Keywords

Examples

			Triangle of compositions begins:
(1),
(11),(2),
(111),(12),(21),(3),
(1111),(112),(121),(211),(13),(22),(31),(4),
(11111),(1112),(1121),(1211),(2111),(113),(122),(131),(212),(221),(311),(14),(23),(32),(41),(5).
		

Crossrefs

Programs

  • Mathematica
    Table[Sort[Join@@Permutations/@IntegerPartitions[n],Or[Length[#1]>Length[#2],Length[#1]===Length[#2]&&OrderedQ[{#1,#2}]]&],{n,6}]

A096903 Least integer of each ordered prime signature (A055932) arranged by prime signature (each row starting with least integer of each prime signature, A025487).

Original entry on oeis.org

1, 2, 4, 6, 8, 12, 18, 16, 24, 54, 30, 32, 36, 48, 162, 60, 90, 150, 64, 72, 108, 96, 486, 120, 270, 750, 128, 144, 324, 180, 300, 450, 192, 1458, 210, 216, 240, 810, 3750, 256, 288, 972, 360, 540, 600, 1350, 1500, 2250, 384, 4374, 420, 630, 1050, 1470, 432, 648
Offset: 0

Views

Author

Ray Chandler, Aug 01 2004

Keywords

Comments

There are several other sequences closely related to a(n). A066099 and A108244 both list the associated exponents, while A108730 provides an elegant mapping to binary representations. - Alford Arnold, Mar 05 2006

Examples

			Sequence begins
1,
2,
4,
6,
8,
12,18,
16,
24,54,
30,
32,
36,
48,162,
60,90,150
		

Crossrefs

Programs

  • Mathematica
    SortBy[#, First] &@ Map[Union@ Map[Times @@ MapIndexed[Prime[First@ #2]^#1 &, #] &, Permutations[#]] &, Map[If[# == 1, {0}, Function[f, ReplacePart[Table[0, {PrimePi[f[[-1, 1]]]}], #] &@ Map[PrimePi@ First@ # -> Last@ # &, f]]@ FactorInteger@ #] &, Import["https://oeis.org/A025487/b025487.txt", "Data"][[1 ;; 30, -1]] ] ] // Flatten (* Michael De Vlieger, Feb 06 2020, using b-file from A025487 *)

Extensions

Edited by Daniel Forgues, Jan 24 2011

A124735 Table with all sequences of nonnegative integers sorted first by total plus length, then by length and finally lexicographically.

Original entry on oeis.org

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

Views

Author

Keywords

Comments

This can be regarded as a table in two ways: with each weak composition as a row, or with the weak compositions of each integer as a row. The first way has A124736 as row lengths and A124748 as row sums; the second has A001792 as row lengths and A001787 as row sums.
This sequence includes every finite sequence of nonnegative integers.

Examples

			The table starts:
0
1; 0 0
2; 0 1; 1 0; 0 0 0
		

Crossrefs

Formula

a(n) = A124734(n) - 1.
Showing 1-6 of 6 results.