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 1-4 of 4 results.

A060857 Describe all the numbers already used (sorted into increasing order - not splitting numbers up into their digits).

Original entry on oeis.org

1, 11, 31, 4113, 612314, 8112332416, 1113253342618, 131528344153628111, 1617210364354648211113, 181921239445661758110311213116, 2211121431146586276829210411112313216118
Offset: 0

Views

Author

Henry Bottomley, May 03 2001

Keywords

Examples

			One; one one; three ones; four ones, one three; six ones, two threes, one four; eight ones, one two, three threes, two fours, one six; eleven ones, three twos, five threes, three fours, two sixes, one eight; thirteen [note not 15] ones, five twos, eight threes, four fours, one five, three sixes, two eights, one eleven [note than numbers >9 are preserved as wholes rather than as a collection of digits]; etc.
		

Crossrefs

This is a combination of methods used in A005151 and A045982. The first word of each term (the number of ones used earlier) seems to be equal to A030711 and A030761.

Programs

  • Haskell
    import Data.List (group, sort, transpose)
    a060857 n = a060857_list !! n
    a060857_list = 1 : f [1] :: [Integer] where
       f xs = (read $ concatMap show ys) : f (xs ++ ys) where
              ys = concat $ transpose [map length zss, map head zss]
              zss = group $ sort xs
    -- Reinhard Zumkeller, Jan 25 2014
    
  • Mathematica
    FromDigits /@ Nest[Append[#, Flatten@ Map[Reverse, Tally@ Sort@ Flatten@ # ] ] &, {{1}}, 10] (* Michael De Vlieger, Jul 15 2020 *)
  • Python
    def summarize_lst(lst):
      ans = []
      for d in sorted(set(lst)): ans += [lst.count(d), d]
      return ans
    def aupton(nn):
      alst, arunninglst = [1], [1]
      for n in range(nn):
        nxt_lst = summarize_lst(arunninglst)
        arunninglst += nxt_lst
        alst.append(int("".join(map(str, nxt_lst))))
      return alst
    print(aupton(10)) # Michael S. Branicky, Jan 11 2021

A045981 Describe all the previous terms!.

Original entry on oeis.org

1, 11, 1121, 1121211211, 112121121121121112211221, 112121121121121112211221211211122112211221123122212211
Offset: 1

Views

Author

Keywords

Comments

Previous terms are described one by one in succession. Next terms are 118, 256, 564 and 1262 digits long.

Crossrefs

Programs

  • Haskell
    a045981 n = a045981_list !! (n-1)
    a045981_list = 1 : f 1 [] where
       f x zs = y : f y zs' where
         y = read (concatMap show zs')
         zs' = zs ++ [a045918 x]
    -- Reinhard Zumkeller, Feb 28 2014

Extensions

More terms from Patrick De Geest, Jun 15 1999

A343837 Describe all the previous terms (previous terms are described one by one in succession; method - digit-indication followed by frequency, initial term is 1).

Original entry on oeis.org

1, 11, 1112, 11121321, 11121321132111312111, 1112132113211131211113211131211231211331112113
Offset: 1

Views

Author

Ilya Gutkovskiy, May 01 2021

Keywords

Comments

The next term is too large to include.

Examples

			a(4) is obtained by saying "1 once; 1 twice; 1 thrice, 2 once", which gives 11121321.
		

Crossrefs

A343838 Describe all the previous terms (previous terms are concatenated into one large integer; method - digit-indication followed by frequency, initial term is 1).

Original entry on oeis.org

1, 11, 13, 1431, 143111413111, 14311141311241311341113113, 14311141311241311341113114413113411131122141113112314113311231
Offset: 1

Views

Author

Ilya Gutkovskiy, May 01 2021

Keywords

Comments

The next term is too large to include.

Examples

			a(4) is obtained by saying "1 four times, 3 once", which gives 1431.
		

Crossrefs

Showing 1-4 of 4 results.