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.

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A030717 The first list after the following procedure: starting with a list [1] and an empty list, repeatedly add the distinct values already in the first list in ascending order to the second list and add the corresponding frequencies of those values to the first list.

Original entry on oeis.org

1, 1, 2, 2, 1, 3, 2, 3, 3, 1, 4, 3, 3, 4, 3, 5, 1, 5, 3, 6, 2, 1, 6, 4, 7, 2, 2, 1, 7, 6, 7, 3, 2, 2, 1, 8, 8, 8, 3, 2, 3, 3, 8, 9, 11, 3, 2, 3, 3, 3, 8, 10, 15, 3, 2, 3, 3, 4, 1, 1, 10, 11, 18, 4, 2, 3, 3, 5, 1, 1, 1, 1, 14, 12, 20, 5, 3, 3, 3, 5, 1, 2, 2, 1
Offset: 1

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Author

Keywords

Comments

The clarifying comment that follows refers to the old name, which was: Row 1, where, at stage k>1, write i in row 1 and j in row 2, where i is the number of j's in row 1, for j=1,2,...,m, where m=max number in row 1 from stages 1 to k-1; state 1 is 1 in row 1.
Numbers j for which the count is 0 are omitted, cf. A333867 for the corresponding sequence where they are included. - Sean A. Irvine, Apr 08 2020

Examples

			First list begins:
  1;
  1;
  2;
  2, 1;
  3, 2;
  3, 3,  1;
  4, 3,  3;
  4, 3,  5, 1;
  5, 3,  6, 2, 1;
  6, 4,  7, 2, 2, 1;
  7, 6,  7, 3, 2, 2, 1;
  8, 8,  8, 3, 2, 3, 3;
  8, 9, 11, 3, 2, 3, 3, 3;
		

Crossrefs

Cf. A030718 (2nd list), A030719 (row lengths), A006920.
Cf. A030707 (repeatedly adds values and frequencies from both lists).
Cf. A333867 (0 counts included, but not the counts of 0s).

Programs

  • Mathematica
    t = {{1}}; Do[AppendTo[t, BinCounts[#, {1, Max[#] + 1}] &[Flatten[t]]], {25}];
    DeleteCases[Flatten[t], 0]  (* Peter J. C. Moses, Apr 09 2020 *)

Extensions

More terms from Franklin T. Adams-Watters, Dec 14 2006
Rolled back to original definition and data by Sean A. Irvine, Apr 08 2020
Name revised in line with A030777 by Peter Munn, Oct 11 2022

A333867 Table with T(1,1) = 1; for n>1, T(n,k) is the number of k's in rows 1 through n-1.

Original entry on oeis.org

1, 1, 2, 2, 1, 3, 2, 3, 3, 1, 4, 3, 3, 4, 3, 5, 1, 5, 3, 6, 2, 1, 6, 4, 7, 2, 2, 1, 7, 6, 7, 3, 2, 2, 1, 8, 8, 8, 3, 2, 3, 3, 8, 9, 11, 3, 2, 3, 3, 3, 8, 10, 15, 3, 2, 3, 3, 4, 1, 0, 1, 10, 11, 18, 4, 2, 3, 3, 5, 1, 1, 1, 0, 0, 0, 1, 14, 12, 20, 5, 3, 3, 3, 5, 1, 2, 2, 0, 0, 0, 1, 0, 0, 1, 17, 14, 23, 5, 5
Offset: 1

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Author

Keywords

Comments

Equivalently, list 1, where, at stage k>1, write i in list 1 and j in list 2, where i is the number of j's in list 1, for j=1,2,...,m, where m=max number in list 1 from stages 1 to k-1; stage 1 is 1 in list 1.
Differs from A030717 in that this sequence includes 0's. - Sean A. Irvine, Apr 08 2020
Nevertheless, this sequence starts each row with the count of 1's, not 0's, whose counts are not recorded in the sequence (cf. A174382, which is also initialized with a 0). - Peter Munn, Oct 11 2022

Examples

			1;
1;
2;
2, 1;
3, 2;
3, 3, 1;
4, 3, 3;
		

Crossrefs

Cf. A126027 (row lengths), A006920, A030717 (zeros suppressed).
Cf. A174382.
Cf. A253170 (row sums).

Programs

  • Haskell
    import Data.List (sort, group)
    a030717 n k = a030717_tabf !! (n-1) !! (k-1)
    a030717_row n = a030717_tabf !! (n-1)
    a030717_tabf = [1] : f [1] where
       f xs = ys : f ((filter (> 0) ys) ++ xs) where
              ys = h (group $ sort xs) [1..] where
                   h [] _ = []
                   h vss'@(vs:vss) (w:ws)
                     | head vs == w = (length vs) : h vss ws
                     | otherwise    = 0 : h vss' ws
    -- Reinhard Zumkeller, Dec 28 2014
  • Mathematica
    t = {{1}}; Do[AppendTo[t, BinCounts[#, {1, Max[#] + 1}] &[Flatten[t]]], {30}];
    Map[Length, t] (* A126027*)
    Map[Total, t]  (* A253170*)
    Flatten[t]     (* A333867 *)  (* Peter J. C. Moses, Apr 09 2020 *)

Extensions

More terms from Franklin T. Adams-Watters, Dec 14 2006

A174831 a(n) is the concatenation of the frequency of 0's, 1's, 2's etc. in the entries a(0) up to a(n-1).

Original entry on oeis.org

0, 1, 11, 13, 1401, 26011, 3811101, 4121210101, 61622201010001, 1119522020100010001, 1922822120100110001001, 27281122120200110001002001, 37331622120200210001002001000011
Offset: 0

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Author

Keywords

Comments

Like A006920 but starting from a(0)=0.

Examples

			a(2) = 1|1 because there is 1 zero and 1 one in the entries a(0) and a(1).
a(3) = 1|3 because there are 1 zero and 3 ones in the entries a(0) to a(2).
a(7) = 4|12|1|2|1|0|1|0|1 because there are 4 zeros, 12 ones, 1 two, 2 threes, 1 four, 0 fives,..., 1 eight in the entries a(0) to a(6).
		

Crossrefs

Extensions

Definition corrected by Paolo P. Lava, Apr 04 2010
Definition rephrased, examples added, keyword:base added - R. J. Mathar, Aug 10 2010
Showing 1-3 of 3 results.