OFFSET
1,1
LINKS
Nathaniel Johnston, Table of n, a(n) for n = 1..10000
EXAMPLE
141 = 3 * 47 is OK because the sets (3) and (4,7) share no digits. 39 = 3 * 13 is rejected because the sets (3) and (1,3) share the digit 3.
MAPLE
with(numtheory): isA052053 := proc(n) local d, dd, m, j, k: if(isprime(n) or not issqrfree(n))then return false: fi: d:=factorset(n): m:=nops(d): for k from 1 to m do dd[k]:=convert(convert(d[k], base, 10), set): od: for j from 1 to m do for k from j+1 to m do if(not dd[j] intersect dd[k] = {})then return false: fi: od: od: return true: end: seq(`if`(isA052053(n), n, NULL), n=2..200); # Nathaniel Johnston, Jun 02 2011
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
Patrick De Geest, Dec 15 1999
STATUS
approved