A248349
Numbers k such that 10^k + 123456789 is prime.
Original entry on oeis.org
4, 11, 17, 23, 26, 79, 82, 221, 526, 821, 1204, 5392, 13139, 35879, 60991, 77669
Offset: 1
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[n: n in [1..500] | IsPrime(10^n + 123456789)]; // Vincenzo Librandi, Oct 12 2014
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Select[Range[10^4], PrimeQ[10^# + 123456789] &] (* Robert Price, Sep 08 2019 *)
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for(n=1,10^4,if(ispseudoprime(10^n + 123456789),print1(n,", ")))
A248350
Numbers n such that 10^n - 123456789 is prime.
Original entry on oeis.org
9, 10, 13, 19, 26, 68, 73, 115, 190, 195, 232, 549, 742, 1502, 2239, 2618, 5143, 8081, 9442, 31402, 77919, 93790, 99434, 120841
Offset: 1
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for(n=1,10^4,if(ispseudoprime(10^n - 123456789),print1(n,", ")))
A248351
Numbers k such that 10^k + 987654321 is prime.
Original entry on oeis.org
6, 11, 15, 27, 42, 113, 135, 186, 207, 503, 2999, 3005, 3487, 5718, 7265, 7629, 11987, 16063, 27379, 64770, 73579, 96504, 116557
Offset: 1
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[n: n in [1..500] | IsPrime(10^n+987654321)]; // Vincenzo Librandi, Oct 12 2014
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Select[Range[1000], PrimeQ[10^# + 987654321] &] (* Vincenzo Librandi, Oct 12 2014 *)
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for(n=1,10^4,if(ispseudoprime(10^n+987654321),print1(n,", ")))
a(9) corrected and a(19)-a(23) added by
Robert Price, Dec 05 2019
Showing 1-3 of 3 results.
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