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.

A002796 Numbers that are divisible by each nonzero digit.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 20, 22, 24, 30, 33, 36, 40, 44, 48, 50, 55, 60, 66, 70, 77, 80, 88, 90, 99, 100, 101, 102, 104, 105, 110, 111, 112, 115, 120, 122, 124, 126, 128, 132, 135, 140, 144, 150, 155, 162, 168, 175, 184, 200, 202, 204, 208, 210, 212
Offset: 1

Views

Author

Keywords

Comments

If n is a member so is 10*n. Also all repunits are members. - Robert G. Wilson v, Apr 12 2015
The repdigits are also members because they're always the repunit number of the same length multiplied by the digit being repeated. - Eric Fox, Sep 02 2019
The number of terms < 10^k: 9, 32, 137, 751, 4577, 29950, 207197, 1495637, ... . - Robert G. Wilson v, Apr 13 2015
Includes all multiples of 2520. - Robert Israel, Apr 15 2015
For n >= 10: A067458(a(n)) = 0. - Reinhard Zumkeller, Sep 24 2015

References

  • Lindon, Visible factor numbers, J. Rec. Math., 1 (1968), 217.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A171492 (complement).
Cf. A067458.

Programs

  • Haskell
    import Data.List (nub, sort); import Data.Char (digitToInt)
    a002796 n = a002796_list !! (n-1)
    a002796_list = filter f [1..] where
       f x = all ((== 0) . mod x) ds where
         ds = map digitToInt (if c == '0' then cs else cs')
         cs'@(c:cs) = nub $ sort $ show x
    -- Reinhard Zumkeller, Jan 01 2014
    
  • Magma
    sol:=[];for k in [1..220] do a:=Set(Intseq(k)) diff {0}; if #[c:c in a|IsIntegral(k/c)] eq #a then; Append(~sol,k); end if; end for; sol; // Marius A. Burtea, Sep 09 2019
    
  • Maple
    select(t -> t mod ilcm(op(convert(convert(t,base,10),set) minus {0})) = 0, [$1..1000]); # Robert Israel, Apr 15 2015
  • Mathematica
    dQ[n_]:=Module[{nzidn=DeleteCases[IntegerDigits[n],0]},And@@Divisible[n, nzidn]]; Select[Range[250],dQ] (* Harvey P. Dale, Dec 13 2011 *)
  • PARI
    is(n)=my(v=vecsort(eval(Vec(Str(n))),,8));for(i=1+(v[1]==0), #v, if(n%v[i],return(0)));1 \\ Charles R Greathouse IV, Apr 17 2012
    
  • Python
    A002796_list = []
    for i in range(1,10**5):
        for d in set(str(i)):
            if d != '0' and i % int(d):
                break
        else:
            A002796_list.append(i) # Chai Wah Wu, Mar 26 2021

Formula

a(n) ~ 2520*n. - Charles R Greathouse IV, Feb 13 2017

Extensions

More terms from Henry Bottomley, Jun 06 2000

A171492 Numbers that are not divisible by each of their nonzero decimal digits.

Original entry on oeis.org

13, 14, 16, 17, 18, 19, 21, 23, 25, 26, 27, 28, 29, 31, 32, 34, 35, 37, 38, 39, 41, 42, 43, 45, 46, 47, 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, 103, 106
Offset: 1

Views

Author

Jaroslav Krizek, Dec 10 2009

Keywords

Comments

Complement of A002796.
A067458(a(n)) > 0. - Reinhard Zumkeller, Sep 24 2015

Crossrefs

Programs

  • Haskell
    import Data.List (nub, sort); import Data.Char (digitToInt)
    a171492 n = a171492_list !! (n-1)
    a171492_list = filter f [1..] where
       f x = any ((> 0) . mod x) ds where
         ds = map digitToInt (if c == '0' then cs else cs')
         cs'@(c:cs) = nub $ sort $ show x
    -- Reinhard Zumkeller, Jan 01 2014
    
  • Magma
    sol:=[];for k in [1..120] do a:=Set(Intseq(k)) diff {0}; if #[c:c in a|IsIntegral(k/c)] ne #a then; Append(~sol,k); end if; end for; sol; // Marius A. Burtea, Sep 09 2019
  • Mathematica
    a[c_]:=Module[{b=DeleteCases[IntegerDigits[c], 0]}, !And@@Divisible[c, b]]; Select[Range[250], a] (* Metin Sariyar, Sep 14 2019 *)

Formula

a(n) ~ k*n, where k = 2520/2519 = 1.00039.... - Charles R Greathouse IV, Feb 13 2017

A088330 Sum of the remainders when n is divided by nonzero numbers obtained by deleting one digit. The sum ranges over all the digits.

Original entry on oeis.org

0, 0, 0, 1, 2, 0, 4, 3, 2, 1, 0, 1, 0, 3, 0, 1, 2, 7, 4, 3, 0, 1, 2, 0, 3, 2, 0, 3, 8, 3, 0, 1, 2, 4, 0, 1, 6, 8, 0, 5, 0, 1, 2, 5, 6, 0, 3, 3, 5, 9, 0, 1, 2, 3, 4, 5, 0, 5, 6, 9, 0, 1, 2, 4, 6, 5, 10, 0, 7, 9, 0, 1, 2, 5, 4, 5, 8, 10, 0, 9, 0, 1, 2, 3, 6, 5, 6, 13, 10, 0, 0, 3, 8, 16, 10, 5, 20, 14, 12, 24, 0
Offset: 10

Views

Author

Amarnath Murthy, Oct 01 2003

Keywords

Comments

Differs from A067458 first at n=101, where A067458(101)=0 and a(101) = (101 mod 1) + (101 mod 11) + (101 mod 10) = 0+2+1 = 3. - R. J. Mathar, Sep 11 2008

Examples

			a(1234) = Rem[1234/123] + Rem[1234/124]+ Rem[1234/134] + Rem[1234/234] = 4+ 118 + 28 + 64 = 214 where Rem [a/b] = the remainder when a is divided by b.
		

Crossrefs

Cf. A000042.

Programs

  • Maple
    f:= proc(n) local L,d,i,j,x,t;
         L:= convert(n,base,10); d:= nops(L); t:= 0;
         for i from 1 to d do
           x:= add(L[j]*10^(j-1),j=1..i-1) + add(L[j]*10^(j-2),j=i+1..d);
           if x <> 0 then t:= t + (n mod x) fi;
         od;
         t
    end proc:
    map(f, [$10 .. 200]); # Robert Israel, Dec 05 2024

Formula

a((10^n - 1)/9) = n. for n > 2. a(1111111 n times ) = a(A000042(n)) = n, n > 2.
a(10 * n) = 10 * a(n). - Robert Israel, Dec 05 2024

Extensions

More terms from Ray Chandler, Oct 06 2003
Showing 1-3 of 3 results.