A181285 Primes of the form 5^k - 4.
3121, 78121, 30517578121, 710542735760100185871124267578121, 413590306276513837435704346034981426782906055450439453121
Offset: 1
Keywords
Examples
3121 = 5^5 - 4 is prime and therefore is in the sequence.
Programs
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Maple
n:=1000: S:={}: for i from 1 to n do if type(5^i-4,prime)=true then S:=S union {5^i-4} end if od; S; -
Mathematica
Select[5^Range[90]-4,PrimeQ] (* Harvey P. Dale, Aug 23 2013 *)