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.

A061827 Number of partitions of n into parts which are the digits of n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 5, 4, 4, 3, 3, 3, 3, 1, 11, 1, 4, 7, 3, 5, 2, 4, 2, 1, 11, 6, 1, 3, 3, 7, 2, 2, 5, 1, 11, 11, 4, 1, 3, 4, 2, 7, 2, 1, 11, 6, 4, 3, 1, 2, 2, 2, 2, 1, 11, 11, 11, 6, 3, 1, 2, 3, 4, 1, 11, 6, 4, 3, 3, 2, 1, 2, 2, 1, 11, 11, 4, 11, 3, 4, 2, 1, 2, 1, 11, 6, 11, 3, 3, 6, 2, 2
Offset: 1

Views

Author

Amarnath Murthy, May 28 2001

Keywords

Comments

a(A125289(n)) = 1, a(A125290(n)) > 1.

Examples

			For n = 11, 1+1+1+1+1+1+1+1+1+1+1. so a(11) = 1. For n = 12, 2+2+2+2+2+2 = 2+2+1+1+1+1+1+1+1+1 = ...etc
a(20) = 1: the only partitions permitted use the digits 0 and 2, so there is just 1, 20 = 2+2+2... ten times.
		

Crossrefs

Programs

  • Haskell
    import Data.List (sort, nub)
    import Data.Char (digitToInt)
    a061827 n =
       p n (map digitToInt $ nub $ sort $ filter (/= '0') $ show n) where
          p _ []        = 0
          p 0 _         = 1
          p m ds'@(d:ds)
            | m < d     = 0
            | otherwise = p (m - d) ds' + p m ds
    -- Reinhard Zumkeller, Aug 01 2011
  • Mathematica
    Length[IntegerPartitions[#,All,DeleteDuplicates@DeleteCases[IntegerDigits[#],0]]]&/@Range[200] (* Sander G. Huisman, Nov 14 2022 *)

Extensions

More terms from David Wasserman, Jul 29 2002

A101594 Numbers with exactly two distinct decimal digits, neither of which is 0.

Original entry on oeis.org

12, 13, 14, 15, 16, 17, 18, 19, 21, 23, 24, 25, 26, 27, 28, 29, 31, 32, 34, 35, 36, 37, 38, 39, 41, 42, 43, 45, 46, 47, 48, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, 64, 65, 67, 68, 69, 71, 72, 73, 74, 75, 76, 78, 79, 81, 82, 83, 84, 85, 86, 87, 89, 91, 92, 93, 94, 95, 96, 97, 98, 112, 113, 114, 115, 116, 117, 118, 119, 121, 122, 131
Offset: 1

Views

Author

David Wasserman, Dec 07 2004

Keywords

Comments

First differs from A125290 at a(83) = 131 != 123 = A101594(83). - Michael S. Branicky, Dec 13 2021

Crossrefs

Programs

  • Haskell
    a101594 n = a101594_list !! (n-1)
    a101594_list = filter ((== 2) . a043537) a052382_list
    -- Reinhard Zumkeller, Jun 18 2013
    
  • Mathematica
    Select[Range[200], FreeQ[#, 0] && Length[Union[#]] == 2 & [IntegerDigits[#]] &] (* Paolo Xausa, May 06 2024 *)
  • Python
    def ok(n): s = set(str(n)); return len(s) == 2 and "0" not in s
    print([k for k in range(132) if ok(k)]) # Michael S. Branicky, Dec 13 2021

Formula

A168046(a(n)) * A043537(A004719(a(n))) = 2. - Reinhard Zumkeller, Jun 18 2013

A125293 Numbers with at least one 1 and one 2 in ternary representation.

Original entry on oeis.org

5, 7, 11, 14, 15, 16, 17, 19, 21, 22, 23, 25, 29, 32, 33, 34, 35, 38, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 57, 58, 59, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 75, 76, 77, 79, 83, 86, 87, 88, 89, 92, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106
Offset: 1

Views

Author

Reinhard Zumkeller, Nov 26 2006

Keywords

Comments

Complement of A125292; A062756(a(n))*A081603(a(n)) > 0;
A125291(a(n)) > 1.

Crossrefs

Programs

  • Mathematica
    Select[Range[120],DigitCount[#,3,1]>0&&DigitCount[#,3,2]>0&] (* Harvey P. Dale, Apr 12 2013 *)
Showing 1-3 of 3 results.