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.

A245680 Numbers x whose digits can be permuted to produce a multiple of x.

Original entry on oeis.org

1035, 1089, 1359, 1386, 1782, 2178, 2475, 10035, 10089, 10350, 10449, 10890, 10899, 10989, 11688, 11883, 12375, 12903, 13029, 13359, 13449, 13590, 13599, 13659, 13860, 13986, 14085, 14247, 14724, 14859, 15192, 16782, 17604, 17802, 17820, 17832, 17982, 18027
Offset: 1

Views

Author

Paolo P. Lava, Jul 29 2014

Keywords

Comments

A008919 is a subset of this sequence.
Every element of the sequence is divisible by 3. - Emmanuel Vantieghem, Oct 27 2015
It is an obvious fact that if a(n) is the n-th term of the sequence, then a(n)*(10^k) is also a member of the sequence for all k > 0. - Altug Alkan, Nov 01 2015

Examples

			A permutation of 1782 is 7128 and 7128 / 1782 = 4.
A permutation of 11688 is 81816 and 81816 / 11688 = 7.
		

Crossrefs

Programs

  • Maple
    P:=proc(q) local a, b, c, i, j, k, n, t; for n from 1 to q do a:=n; b:=[];
    while a>0 do b:=[a mod 10, op(b)]; a:=trunc(a/10); od;
    t:=0; for i from 2 to 9 do a:=i*n; c:=[];
    while a>0 do c:=[a mod 10, op(c)]; a:=trunc(a/10); od;
    if sort(b)=sort(c) then print(n); break; fi; od; od; end: P(10^6);
    # Alternative:
    N:= 100: # to get the first N entries
    count:= 0:
    for x from 10 while count < N do
      M:= 10^(ilog10(x)+1)-1;
      L:= sort(convert(x,base,10));
      for i from 2 to floor(M/x) do
        Lp:= sort(convert(i*x,base,10));
        if Lp = L then
          count:= count+1;
          A[count]:= x;
          break;
        fi
       od
    od:
    seq(A[i],i=1..count); # Robert Israel, Jul 29 2014
  • Mathematica
    fQ[n_] := AnyTrue[Rest[FromDigits /@ Permutations[IntegerDigits@ n]], Divisible[#, n] &]; Select[Range@ 20000, fQ] (* Michael De Vlieger, Oct 27 2015, Version 10 *)
  • PARI
    for(n=1,10^8,d=vecsort(digits(n));p=0;for(k=2,9,dd=vecsort(digits(n*k));if(d==dd,p++;break));if(p>0,print1(n,", "))) \\ quicker program Derek Orr, Jul 29 2014
  • Python
    import itertools
    from itertools import permutations
    for n in range(1,10**5):
      plist = list(permutations(str(n)))
      for i in plist:
        num = ''
        for j in range(len(i)):
          num += i[j]
        if int(num)%n==0 and int(num)/n > 1:
          print(n,end=', ') # Derek Orr, Jul 29 2014