A245442
Numbers n such that (50^n - 1)/49 is prime.
Original entry on oeis.org
3, 5, 127, 139, 347, 661, 2203, 6521, 210319
Offset: 1
Cf.
A028491,
A004061,
A004062,
A004063,
A004023,
A005808,
A004064,
A016054,
A006032,
A006033,
A006034,
A006035,
A127995,
A127996,
A127997,
A127998,
A127999,
A098438,
A128002,
A128003,
A128004,
A128005,
A240765,
A242797,
A243279,
A245237.
a(9)=210319 corresponds to a probable prime discovered by
Paul Bourdelais, Aug 04 2020
A181987
Numbers n such that (39^n - 1)/38 is prime.
Original entry on oeis.org
349, 631, 4493, 16633, 36341
Offset: 1
Cf.
A028491,
A004061,
A004062,
A004063,
A004023,
A005808,
A004064,
A016054,
A006032,
A006033,
A006034,
A006035,
A127995,
A127996,
A127997,
A127998,
A127999,
A098438,
A128002,
A128003,
A128004,
A128005.
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Select[Prime[Range[100000]], PrimeQ[(39^#-1)/38]&]
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is(n)=ispseudoprime((39^n-1)/38) \\ Charles R Greathouse IV, Jun 13 2017
A185073
Numbers n such that (34^n - 1)/33 is prime.
Original entry on oeis.org
13, 1493, 5851, 6379, 125101
Offset: 1
Cf.
A028491,
A004061,
A004062,
A004063,
A004064,
A004023,
A005808,
A016054,
A006032,
A006033,
A006034,
A006035,
A098438,
A127995-
A128005.
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Select[Prime[Range[100]], PrimeQ[(34^#-1)/33]&]
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isok(n) = isprime((34^n-1)/33); \\ Michel Marcus, Mar 13 2016
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lista(nn) = for(n=1, nn, if(ispseudoprime((34^n - 1)/33), print1(n, ", "))); \\ Altug Alkan, Mar 13 2016
a(5)=125101 corresponds to a probable prime discovered by
Paul Bourdelais, Nov 20 2017
A294722
Numbers k such that (44^k - 1)/43 is prime.
Original entry on oeis.org
5, 31, 167, 100511
Offset: 1
Cf.
A028491,
A004061,
A004062,
A004063,
A004023,
A005808,
A004064,
A016054,
A006032,
A006033,
A006034,
A006035,
A127995,
A127996,
A127997,
A127998,
A127999,
A098438,
A128002,
A128003,
A128004,
A128005,
A240765.
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ParallelMap[ If[ PrimeQ[(44^# - 1)/43], #, Nothing] &, Prime@Range @ 10000] (* Robert G. Wilson v, Nov 25 2017 *)
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is(n) = ispseudoprime((44^n-1)/43) \\ Felix Fröhlich, Nov 08 2017
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ABC2 (44^$a-1)/43 // -f{2*$a}
a: primes from 2 to 1000000
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