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.

A057880 Primes with 4 distinct digits that remain prime (no leading zeros allowed) after deleting all occurrences of its digits d.

Original entry on oeis.org

6173, 12239, 16673, 19531, 19973, 21613, 22397, 22937, 34613, 36137, 47933, 51193, 54493, 56519, 56531, 56591, 69491, 69497, 72937, 76873, 93497, 96419, 96479, 96497, 98837, 112939, 118213, 131779, 143419, 144497, 159319, 163337
Offset: 1

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Author

Patrick De Geest, Oct 15 2000

Keywords

Crossrefs

Programs

  • Maple
    filter:= proc(L) local d,Lp,i;
          if L[-1]=0 then return false fi;
          if not isprime(add(L[i]*10^(i-1),i=1..nops(L))) then return false fi;
          for d in convert(L,set) do
            Lp:= remove(`=`,L,d);
            if Lp[-1] = 0 or not isprime(add(Lp[i]*10^(i-1),i=1..nops(Lp))) then return false fi;
          od;
          true
    end proc:
    getCands:= proc(n, m) option remember;
       if m = 1 then return [seq([d$n], d=0..9)] fi;
       if n < m then return [] fi;
       [seq(seq([i,op(L)],i= {$0..9} minus convert(L,set)),L = procname(n-1,m-1)),
        seq(seq([i,op(L)],i=convert(L,set)),L = procname(n-1,m))]
    end proc:
    [seq(op(sort(map(t->add(t[i]*10^(i-1),i=1..nops(t)),select(filter,getCands(d,4))))),d=4..6)]; # Robert Israel, Jan 19 2017
  • Mathematica
    p4dQ[n_]:=Module[{idn=IntegerDigits[n]},Count[idn,0]==0 && Count[ DigitCount[ n],0]==6&&AllTrue[FromDigits/@Table[DeleteCases[idn,k],{k,Union[idn]}],PrimeQ]]; Select[Prime[Range[ 15000]],p4dQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 30 2017 *)

Extensions

Offset changed by Robert Israel, Jan 19 2017