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A244607
Numbers k such that (product of digits of k) - 1 is prime.
1
3, 4, 6, 8, 13, 14, 16, 18, 22, 23, 24, 26, 27, 29, 31, 32, 34, 36, 38, 41, 42, 43, 45, 46, 48, 54, 56, 61, 62, 63, 64, 65, 67, 68, 69, 72, 76, 81, 83, 84, 86, 89, 92, 96, 98, 113, 114, 116, 118, 122, 123, 124, 126, 127, 129, 131, 132, 134, 136, 138, 141, 142, 143, 145, 146
OFFSET
1,1
COMMENTS
This sequence is infinite. With any number a(n), you can add infinitely many 1's to its decimal representation. E.g., 32 is in this sequence, so 321, 312, 3211, 32111, 31121, 11321, etc. are also terms of this sequence.
A number k is a term of this sequence iff A007954(k) is in A008864.
LINKS
EXAMPLE
3*2 - 1 = 5 is prime. Thus 32 is a term of this sequence.
PROG
(PARI) for(n=1, 10^3, d=digits(n); p=prod(i=1, #d, d[i]); if(isprime(p-1), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Derek Orr, Jul 01 2014
EXTENSIONS
Wrong term removed by Jens Kruse Andersen, Jul 13 2014
STATUS
approved