A093765
Numbers k such that 6^k+5^(k-1) is prime.
Original entry on oeis.org
1, 2, 3, 8, 9, 15, 26, 30, 69, 212, 318, 909, 1224, 1946, 2192, 2234, 2978, 3344, 4976, 7947, 8079, 23334, 23624, 55401, 89712
Offset: 1
Herman H. Rosenfeld (herm3(AT)pacbell.net), May 17 2004
15 is a member since 615+515 = 476288500201 which is a prime number.
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Do[ If[ PrimeQ[6^n + 5^(n - 1)], Print[n]], {n, 4000}]
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is(n)=isprime(6^n+5^(n-1)) \\ Charles R Greathouse IV, Feb 17 2017
A271883
Numbers n such that 9^n-8^(n-1) is prime.
Original entry on oeis.org
2, 22, 58, 496, 2740
Offset: 1
2 is a member since 9^2 - 8^1 = 81 - 8 = 73 which is a prime number.
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Select[Range[0, 100000], PrimeQ[9^# - 8^(# - 1)] &]
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lista(nn) = for(n=1, nn, if(ispseudoprime(9^n-8^(n-1)), print1(n, ", "))); \\ Altug Alkan, Apr 16 2016
A271884
Numbers n such that 4^n-3^(n-1) is prime.
Original entry on oeis.org
1, 2, 4, 6, 10, 12, 30, 42, 54, 166, 264, 886, 1476, 8412, 9576, 12426, 24076
Offset: 1
4 is a member since 4^4 - 3^3 = 256 - 27 = 229 which is a prime number.
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Select[Range[0, 100000], PrimeQ[4^# - 3^(# - 1)] &]
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lista(nn) = for(n=1, nn, if(ispseudoprime(4^n-3^(n-1)), print1(n, ", "))); \\ Altug Alkan, Apr 16 2016
A272345
Numbers n such that 8^n-7^(n-1) is prime.
Original entry on oeis.org
1, 3, 5, 29, 41, 83, 471, 725, 1277, 10271, 15069, 97731
Offset: 1
5 is a member since 8^5 - 7^4 = 32768 - 2401 = 30367 which is a prime number.
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Select[Range[0, 100000], PrimeQ[8^# - 7^(# - 1)] &]
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is(n)=ispseudoprime(8^n-7^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017
A272272
Numbers k such that 4^k-3^(k+1) is prime.
Original entry on oeis.org
4, 8, 24, 36, 48, 246, 608, 734, 774, 824, 948, 1244, 3230, 4656, 5448, 6360, 7598, 15390, 48158, 86754
Offset: 1
8 is a member since 4^8 - 3^9 = 65536-19683 = 45853 which is a prime number.
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Select[Range[4, 100000], PrimeQ[4^# - 3^(# + 1)] &]
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lista(nn) = for(n=1, nn, if(ispseudoprime(4^n-3^(n+1)), print1(n, ", "))); \\ Altug Alkan, Apr 24 2016
A272296
Numbers n such that 5^n-4^(n-1) is prime.
Original entry on oeis.org
3, 11, 25, 341, 1827, 2581, 4475, 11157, 41141, 64721
Offset: 1
3 is a member since 5^3 - 4^2 = 125 - 16 = 109 which is a prime number.
Cf.
A093713,
A082103,
A093717,
A093793,
A096185,
A093794,
A093795,
A096186,
A271883,
A271884,
A272345.
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Select[Range[0, 100000], PrimeQ[5^# - 4^(# - 1)] &]
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is(n)=ispseudoprime(5^n-4^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017
A272366
Numbers n such that 5^n-4^(n+1) is prime.
Original entry on oeis.org
7, 25, 29, 55, 75, 243, 345, 635, 899, 2025, 2105, 2295, 5057, 5155, 5209, 11115, 81743, 97615
Offset: 1
7 is a member since 5^7 - 4^8 = 78125 - 65536 = 12589 which is a prime number.
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Select[Range[0, 100000], PrimeQ[5^# - 4^(# + 1)] &]
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is(n)=ispseudoprime(5^n-4^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017
A272621
Numbers n such that 10^n-9^(n-1) is prime.
Original entry on oeis.org
3, 9, 15, 155, 217, 281, 287, 491, 563, 581, 983, 2243, 4375, 8409, 98669
Offset: 1
3 is a member since 10^3-9^2 = 1000-81 = 919 which is a prime number.
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Select[Range[0, 100000], PrimeQ[10^# - 9^(# - 1)] &]
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is(n)=ispseudoprime(10^n-9^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017
A272781
Numbers n such that 6^n-5^(n+1) is prime.
Original entry on oeis.org
9, 14, 32, 48, 78, 85, 108, 134, 834, 1701, 2275, 3103, 5795, 10307, 17243, 24045, 31085, 32613, 40014
Offset: 1
9 is a member since 6^9 - 5^10 = 10077696 - 9765625 = 312071 which is a prime number.
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Select[Range[0, 100000], PrimeQ[6^# - 5^(# + 1)] &]
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is(n)=ispseudoprime(6^n-5^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017
A272829
Numbers n such that 8^n-7^(n+1) is prime.
Original entry on oeis.org
27, 43, 61, 105, 835, 2313, 5907, 32455, 33657
Offset: 1
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Select[Range[15,100000],PrimeQ[8^# - 7^(# + 1)]]
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is(n)=ispseudoprime(8^n-7^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017
Showing 1-10 of 15 results.
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