

A261579


Numbers m such that (4^m + 23) / 3 is prime.


1



2, 3, 5, 6, 27, 47, 66, 77, 83, 105, 197, 231, 293, 702, 1692, 3021, 6270, 6897, 7733, 14537, 15797, 21083, 21276, 28817, 65430, 111231, 137405, 141017, 185225
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OFFSET

1,1


COMMENTS

a(30) > 450,000.  Robert Price, Oct 04 2018


LINKS

Table of n, a(n) for n=1..29.


EXAMPLE

2 is in the sequence because (4^2 + 23)/3 = 13 is prime.
3 is in the sequence because (4^3 + 23)/3 = 29 is prime.


MATHEMATICA

Select[Range[0, 5000], PrimeQ[(4^# + 23)/3] &]


PROG

(MAGMA) [n: n in [0..1500]  IsPrime((4^n+23) div 3)];


CROSSREFS

Cf. similar sequences listed in A261539.
Sequence in context: A131599 A263650 A076384 * A270517 A124648 A093339
Adjacent sequences: A261576 A261577 A261578 * A261580 A261581 A261582


KEYWORD

nonn,more


AUTHOR

Vincenzo Librandi, Aug 27 2015


EXTENSIONS

a(17)a(28) from Robert Price, Feb 01 2017
a(29) from Robert Price, Oct 04 2018


STATUS

approved



