A078239 a(n) = smallest multiple of n using only prime digits, with a(n) = 0 if there are none.

2, 2, 3, 32, 5, 72, 7, 32, 27, 0, 22, 72, 52, 252, 75, 32, 255, 72, 57, 0, 252, 22, 23, 72, 25, 52, 27, 252, 232, 0, 372, 32, 33, 272, 35, 72, 37, 532, 273, 0, 533, 252, 2322, 352, 225, 322, 235, 2352, 735, 0, 255, 52, 53, 2322, 55, 2352, 57, 232, 2537, 0, 732, 372, 252, 2752, 325, 2772, 335, 272

Offset

1,1

Comments

Besides multiples of 10, 625 and its odd multiples have a(n)=0. - Robert Israel, Feb 12 2018

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

f := proc (n) local k, k10, j;
  if n mod 10 = 0 or n mod 625 = 0 then return 0 end if;
  k10 := select(t -> member(t*n mod 10, {2, 3, 5, 7}), [$1 .. 9]);
  for j from 0 do
    for k in k10 do
      if convert(convert((10*j+k)*n, base, 10), set) subset {2, 3, 5, 7}
      then return (10*j+k)*n
      fi
od od
end proc:
map(f, [$1..100]; # Robert Israel, Feb 12 2018

Crossrefs

Sequence in context: A074935 A320103 A212796 * A083113 A184847 A354743

Adjacent sequences: A078236 A078237 A078238 * A078240 A078241 A078242

Keyword

base,easy,nonn

Author

Amarnath Murthy, Nov 23 2002

Extensions

Edited and more terms from Robert Israel, Feb 12 2018

Status

approved