A253772
Numbers k such that 4^k + 13 is prime.
Original entry on oeis.org
1, 2, 4, 10, 19, 32, 40, 146, 566, 2054, 9967, 62639, 87814, 141092
Offset: 1
Cf. Numbers k such that 4^k + d is prime:
A089437 (d=3),
A217349 (d=7),
A217350 (d=9), this sequence (d=13),
A253773 (d=15),
A253774 (d=19),
A262345 (d=21),
A204388 (d=25),
A262969 (d=27),
A262971 (d=31),
A262972 (d=33).
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[n: n in [0..2000] | IsPrime(4^n+13)];
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Select[Range[4000], PrimeQ[4^# + 13] &]
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is(n)=ispseudoprime(4^n+13) \\ Charles R Greathouse IV, Feb 17 2017
A228027
Primes of the form 4^k + 9.
Original entry on oeis.org
13, 73, 1033, 262153, 1073741833, 73786976294838206473, 4835703278458516698824713
Offset: 1
262153 is a term because 4^9 + 9 = 262153 is prime.
Cf. Primes of the form r^k + h:
A092506 (r=2, h=1),
A057733 (r=2, h=3),
A123250 (r=2, h=5),
A104066 (r=2, h=7),
A104070 (r=2, h=9),
A057735 (r=3, h=2),
A102903 (r=3, h=4),
A102870 (r=3, h=8),
A102907 (r=3, h=10),
A290200 (r=4, h=1),
A228026 (r=4, h=3), this sequence (r=4, h=9),
A182330 (r=5, h=2),
A228029 (r=5, h=6),
A102910 (r=5, h=8),
A182331 (r=6, h=1),
A104118 (r=6, h=5),
A104115 (r=6, h=7),
A104065 (r=7, h=4),
A228030 (r=7, h=6),
A228031 (r=7, h=10),
A228032 (r=8, h=3),
A228033 (r=8, h=5),
A144360 (r=8, h=7),
A145440 (r=8, h=9),
A228034 (r=9, h=2),
A159352 (r=10, h=3),
A159031 (r=10, h=7).
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[a: n in [0..200] | IsPrime(a) where a is 4^n+9];
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Select[Table[4^n + 9, {n, 0, 200}],PrimeQ]
Showing 1-2 of 2 results.
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