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 1-5 of 5 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

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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

A119246 Numbers containing in decimal representation their digital root.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 19, 20, 29, 30, 39, 40, 49, 50, 59, 60, 69, 70, 79, 80, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 109, 118, 127, 128, 136, 138, 145, 148, 154, 158, 163, 168, 172, 178, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 198, 199, 200
Offset: 1

Views

Author

Reinhard Zumkeller, May 10 2006

Keywords

Comments

Complement of A119247.
For terms u: all digital permutations of u form terms; u*10 and all insertions of 0 are terms; if v is another term, then the concatenations uv, vu are also terms, as well as all insertions of v in u; these properties allow the construction of all terms beginning with {d:1<=d<=9}. - Reinhard Zumkeller, May 19 2006

Crossrefs

Programs

  • Haskell
    a119246 n = a119246_list !! (n-1)
    a119246_list =
        filter (\x -> a010888 x `elem` a031298_row (fromInteger x)) [0..]
    -- Reinhard Zumkeller, Dec 16 2013, Apr 14 2011
  • Mathematica
    d[n_] := IntegerDigits[n]; Select[Range[0, 200], MemberQ[d[#1], NestWhile[Total[d[#]] &, #1, # > 9 &]] &] (* Jayanta Basu, Jul 13 2013 *)

A038528 If n has decimal expansion abc...d, with k digits, let f(n) be obtained by deleting all k's from abc...d, closing up and deleting initial 0's; sequence gives n such that f(f(f(...(n)))) = 0 or empty.

Original entry on oeis.org

1, 12, 20, 21, 22, 123, 132, 133, 203, 213, 223, 230, 231, 232, 300, 301, 303, 312, 313, 320, 321, 322, 330, 331, 333, 1234, 1243, 1244, 1324, 1334, 1342, 1343, 1423, 1424, 1432, 1433, 1442, 1444, 2034, 2043, 2044, 2134, 2143, 2144, 2234
Offset: 1

Views

Author

Keywords

Comments

The sequence has exactly 14174521 terms, 999999999 is the last and largest. - Reinhard Zumkeller, Jul 04 2012

Examples

			If n=22 (2 digits), f(n) = empty. If n=230 (3 digits), f(n)=20, f(f(n))=0. If n=301 (3 digits), f(n)=1 (1 digit), f(f(n))=empty.
The last 12 terms are: 999999333, 999999900, 999999901, 999999909, 999999912, 999999919, 999999920, 999999921, 999999922, 999999990, 999999991, 999999999.
		

Crossrefs

Cf. A038527.
Cf. A002024, A055642, A031298, subsequence of A138166.

Programs

  • Haskell
    import Data.List ((\\))
    a038528 n = a038528_list !! (n-1)
    a038528_list = gen ([1], 1) where
       gen (_, 10) = []
       gen (ds, len)
          | len `elem` ds && chi ds
            = foldr (\u v -> u + 10*v) 0 ds : gen (succ (ds, len))
          | otherwise = gen (succ (ds, len))
       chi xs = null ys || ys /= xs && chi ys where
                ys = tr $ filter (/= length xs) xs
                tr zs = if null zs || last zs > 0 then zs else tr $ init zs
       succ ([], len)   = ([1], len + 1)
       succ (d : ds, len)
           | d < len = (head (dropWhile (<= d) a002024_list \\ ds) : ds, len)
           | otherwise = (0 : ds', len') where (ds', len') = succ (ds, len)
    -- Reinhard Zumkeller, Jul 04 2012
  • Mathematica
    zeroQ[n_] :=  FixedPoint[ Function[{k}, DeleteCases[id = IntegerDigits[k], Length[id]] // FromDigits[#, 10]&], n] == 0; Select[Range[10^4], zeroQ] (* Jean-François Alcover, Dec 10 2014 *)

Formula

A054055(a(n)) = A055642(a(n)). - Reinhard Zumkeller, Jul 04 2012

A138167 Numbers containing their length in ternary representation.

Original entry on oeis.org

1, 5, 6, 7, 8, 9, 10, 11, 12, 21, 31, 36, 37, 38, 39, 40, 41, 42, 43, 44, 49, 58, 66, 67, 68, 76, 86, 95, 96, 97, 98, 104, 113, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 03 2008

Keywords

Examples

			42 ->'1120', length = 4 ->'11', therefore 42 is a term;
420 ->'120120', length = 6 ->'20', therefore 420 is a term.
		

Crossrefs

A138168 Numbers containing their length in binary representation.

Original entry on oeis.org

1, 2, 6, 7, 8, 9, 12, 20, 21, 22, 23, 26, 27, 29, 38, 44, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 71, 78, 79, 87, 92, 93, 94, 95, 103, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 03 2008

Keywords

Examples

			20 ->'10100', length = 5 ->'101', therefore 20 is a term;
200 ->'11001000', length = 8 ->'1000', therefore 200 is a term.
		

Crossrefs

Programs

  • Mathematica
    lbrQ[n_]:=Module[{idn2=IntegerDigits[n,2]},SequenceCount[idn2, IntegerDigits[ Length[ idn2],2]]>0]; Select[Range[200],lbrQ] (* The program uses the SequenceCount function from Mathematica version 10 *) (* Harvey P. Dale, Oct 07 2015 *)
Showing 1-5 of 5 results.