A261579 - OEIS

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A261579

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

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: A263650 A345709 A076384 * A376655 A270517 A124648

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