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A241681
Numbers n such that the decimal digits of n are also the prime divisors of n.
0
2, 3, 5, 7, 735, 2333772
OFFSET
1,1
COMMENTS
The sequence is given for a(n) < 10^11.
No more terms <= 10^150. Terms are of the form 2^e2 * 3^e3 * 7^e7 or of the form 3^e3 * 5^e5 * 7^e7, for which no other number <= 10^150 than those listed is a term. - David A. Corneth, Sep 28 2019
EXAMPLE
735 = 3*5*7^2 is in the sequence because the digits 7, 3 and 5 are also the prime divisors of 735.
MAPLE
with(numtheory):nn:=1000000:for n from 1 to 10^11 do:lst:={}:x:=factorset(n):y:=convert(n, base, 10):n1:=nops(x):n2:=nops(y): for j from 1 to n2 do:lst:=lst union {y[j]}:od:if x=lst then print(n):else fi:od:
CROSSREFS
Subsequence of A046034.
Sequence in context: A145843 A090720 A114780 * A134811 A046479 A109208
KEYWORD
nonn,base,hard
AUTHOR
Michel Lagneau, Apr 27 2014
STATUS
approved