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
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 23 2002
EXTENSIONS
Edited and more terms from Robert Israel, Feb 12 2018
STATUS
approved