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.

A052018 Numbers k with the property that the sum of the digits of k is a substring of k.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 109, 119, 129, 139, 149, 159, 169, 179, 189, 199, 200, 300, 400, 500, 600, 700, 800, 900, 910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 1000, 1009, 1018, 1027, 1036, 1045, 1054, 1063
Offset: 1

Views

Author

Patrick De Geest, Nov 15 1999

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List (isInfixOf)
    a052018 n = a052018_list !! (n-1)
    a052018_list = filter f [0..] where
       f x = show (a007953 x) `isInfixOf` show x
    -- Reinhard Zumkeller, Jun 18 2013
    
  • Mathematica
    sdssQ[n_]:=Module[{idn=IntegerDigits[n],s,len},s=Total[idn];len= IntegerLength[ s]; MemberQ[Partition[idn,len,1],IntegerDigits[s]]]; Join[{0},Select[Range[1100],sdssQ]] (* Harvey P. Dale, Jan 02 2013 *)
  • Python
    loop = (str(n) for n in range(399))
    print([int(n) for n in loop if str(sum(int(k) for k in n)) in n]) # Jonathan Frech, Jun 05 2017

A138166 Numbers containing their length in their decimal representation.

Original entry on oeis.org

1, 12, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 32, 42, 52, 62, 72, 82, 92, 103, 113, 123, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 143, 153, 163, 173, 183, 193, 203, 213, 223, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 243, 253, 263, 273, 283
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 03 2008

Keywords

Crossrefs

Cf. A038528 (subsequence).

Programs

  • Haskell
    import Data.List (isInfixOf)
    a138166 n = a138166_list !! (n-1)
    a138166_list = filter (\x -> show (a055642 x) `isInfixOf` show x) [0..]
    -- Reinhard Zumkeller, Jul 04 2012

A119247 Numbers not containing their digital root in decimal representation.

Original entry on oeis.org

11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 23, 24, 25, 26, 27, 28, 31, 32, 33, 34, 35, 36, 37, 38, 41, 42, 43, 44, 45, 46, 47, 48, 51, 52, 53, 54, 55, 56, 57, 58, 61, 62, 63, 64, 65, 66, 67, 68, 71, 72, 73, 74, 75, 76, 77, 78, 81, 82, 83, 84, 85, 86, 87, 88, 101
Offset: 1

Views

Author

Reinhard Zumkeller, May 10 2006

Keywords

Comments

Complement of A119246.
The ISO human tooth numbering consists of the first 32 terms of this sequence. - Jean-François Alcover, Sep 12 2015

Crossrefs

Cf. A010888.

Programs

  • Maple
    A119247 := proc(n) option remember: local k: if(n=1)then return 11:fi: for k from procname(n-1)+1 do if(not ((k-1) mod 9) + 1 in convert(convert(k,base,10),set))then return k: fi: od: end: seq(A119247(n), n=1..65); # Nathaniel Johnston, May 05 2011
  • Mathematica
    d[n_] := IntegerDigits[n]; Select[Range[101], FreeQ[d[#1], NestWhile[Total[d[#]] &, #1, # > 9 &]] &] (* Jayanta Basu, Jul 13 2013 *)

A371123 Numbers whose decimal representation contains the digital root of the product of their digits.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 29, 30, 31, 34, 37, 39, 40, 41, 43, 46, 49, 50, 51, 59, 60, 61, 64, 67, 69, 70, 71, 73, 76, 79, 80, 81, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112
Offset: 1

Views

Author

Saish S. Kambali, Mar 11 2024

Keywords

Comments

All numbers with a 0 digit (A011540) are terms, since their product of digits is 0.
All numbers with a 9 digit (A011539) are terms, since their product of digits is a multiple of 9 and so has digital root 9 if no 0 digits, or 0 if any 0 digit.

Examples

			29 is a term because 2*9=18 and 1+8=9 and 29 contains digit 9.
		

Crossrefs

Programs

  • Mathematica
    digRoot[n_] := If[n == 0, 0, Mod[n - 1, 9] + 1]; q[n_] := Module[{d = IntegerDigits[n]}, MemberQ[d, digRoot[Times @@ d]]]; Select[Range[0, 112], q] (* Amiram Eldar, Mar 11 2024 *)
Showing 1-4 of 4 results.