1,2

a(6) corresponds to a prime having 153 digits.

If it exists, a(7) > 5000.

n does not have the form 20k+2 (which leads to a multiple of 5) or 42k+26 (which leads to a multiple of 7).

Table of n, a(n) for n=1..6.

4 is in the sequence because 4^4 - 3^4 + 4 = 179 is prime.

Select[Range[1000], PrimeQ[#^# - (# - 1)^# + #] &]

(MAGMA) [n: n in [0..500] |IsPrime(n^n - (n-1)^n + n)];

(PARI) is(n)=ispseudoprime(n^n-(n-1)^n+n) \\ Charles R Greathouse IV, Jun 13 2017

Cf. A085682.

Sequence in context: A104354 A153948 A284730 * A010362 A262164 A322940

Adjacent sequences: A255727 A255728 A255729 * A255731 A255732 A255733

nonn,more

Vincenzo Librandi, Mar 13 2015

approved