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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 (list; graph; refs; listen; history; text; internal format)
 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 Jens Kruse Andersen, Table of n, a(n) for n = 1..10000 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 Cf. A007954, A008864, A089377, A081988. Sequence in context: A146566 A204658 A139041 * A136483 A240494 A280250 Adjacent sequences:  A244604 A244605 A244606 * A244608 A244609 A244610 KEYWORD nonn,base,easy AUTHOR Derek Orr, Jul 01 2014 EXTENSIONS Wrong term removed by Jens Kruse Andersen, Jul 13 2014 STATUS approved

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Last modified January 20 14:51 EST 2021. Contains 340302 sequences. (Running on oeis4.)