

A265483


Numbers k such that 25^k  5^k  1 is prime.


1



1, 2, 4, 15, 16, 24, 57, 206, 284, 1290, 1722, 1862, 1866, 3271, 5306, 5474, 15401, 18729, 34757, 42842, 63930, 89967
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OFFSET

1,2


COMMENTS

For k = 1, 2, 4, 15, 16, the corresponding primes are 19, 599, 389999, 931322574584960937499, 23283064365234374999999.
a(n) is not of the form 5*m + 3 (divisibility by 11) or 9*m + 10 (divisibility by 19), 7*m + (1)^m + 7 (divisibility by 29) or 29*m + 27 (divisibility by 59).


LINKS



EXAMPLE

4 is in the sequence because 25^45^41 = 389999 is prime.


MATHEMATICA

Select[Range[6000], PrimeQ[25^#  5^#  1] &]


PROG

(Magma) [n: n in [0..300]  IsPrime(25^n5^n1)];


CROSSREFS

Cf. similar sequences listed in A265481.


KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



