

A083359


Visible Factor Numbers, or VFNs: numbers n with the property that every prime factor of n can be found in the decimal expansion of n and every digit of n can be found in a prime factor.


11



735, 3792, 13377, 21372, 51375, 119911, 229912, 290912, 537975, 1341275, 1713192, 2333772, 2971137, 4773132, 7747292, 13115375, 13731373, 19853575, 22940075, 29090912, 29373375, 31373137, 35322592, 52979375, 71624133, 79241575
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Larger terms can be found with the factorization of 10^m+1. A prime p containing all the prime factors of 10^m+1 will give the VFN (pp), for example 13731373 = 73*137*1373 with 73*137 = 10001. Every prime 9090...9091 builds a VFN with the cofactor 2^5.
Sequence is probably infinite.
The prime p in the 10^m+1 example above must contain exactly m digits. Also, it can contain one of the prime factors wrapped around the end of p. For example, p=11909 contains 11 and 9091, the factors of 100001, with the 9091 wrapping around to the beginning of p. This forms a(44)=1190911909.  Deron Stewart, Feb 23 2019
The concatenation must be possible using the prime factors of the number, unlimited multiplicity of the distinct prime factors is not allowed. For example, 71153775 = 3*3*3*5*5*7*11*37*37 can be formed by 71153775 but the concatenation requires two 7's and there is only one 7 in the prime factorization, so it is not in the sequence.  Deron Stewart, Mar 01 2019


REFERENCES

Lindon, Visible factor numbers, J. Rec. Math., 1 (1968), 217.


LINKS

Giovanni Resta, Table of n, a(n) for n = 1..165 (first 64 terms except a(59) from Sven Simon, a(59) and a(64)a(74) from Deron Stewart)


CROSSREFS

Cf. A083360, A083361.
Sequence in context: A227755 A096595 A324257 * A324258 A083360 A324260
Adjacent sequences: A083356 A083357 A083358 * A083360 A083361 A083362


KEYWORD

nonn,base


AUTHOR

Sven Simon, Apr 27 2003


STATUS

approved



