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A288491
Numbers k such that k^k*prime(k) - 1 is prime.
0
2, 6, 40, 56, 954
OFFSET
1,1
COMMENTS
a(6) > 22000. - Giovanni Resta, Jun 12 2017
EXAMPLE
a(1) = 2 because 3*2^2-1 = 11 a prime.
a(2) = 6 because 13*6^6-1 = 606527 a prime.
MATHEMATICA
Select[Range[1000], PrimeQ[Prime[#] #^# - 1] &]
PROG
(Magma) [n: n in [1..1000] | IsPrime(NthPrime(n)*n^n-1)];
CROSSREFS
Cf. A086173.
Sequence in context: A340299 A068207 A331702 * A212883 A377855 A336959
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Jun 10 2017
STATUS
approved