A364484 Numbers whose prime factorization (prime factors and exponents) contains the digits 1 and 2 at least once, but no other digits.
2, 22, 44, 121, 211, 242, 422, 484, 844, 2048, 2111, 2221, 2321, 4096, 4222, 4442, 4642, 8444, 8884, 9284, 12211, 21121, 21211, 21221, 22111, 22528, 23221, 24422, 24431, 25531, 42242, 42422, 42442, 44222, 44521, 45056, 46442, 48844, 48862, 51062, 84484, 84844, 84884, 88444, 89042, 92884, 97724
Offset: 1
Examples
9284 is a term because 9284 = 2^2 * 11^1 * 211^1.
Crossrefs
Cf. A007931.
Programs
-
PARI
for(n=1, 1e5, v=[]; s=Set(v); f=factor(n); k=#f[, 1]; for(i=1, k, s1=Set(digits(f[i, 1])); s=setunion(s, s1)); for(i=1, k, s2=Set(digits(f[i, 2])); s=setunion(s, s2)); if(s==[1, 2], print1(n, ", ")))