login
A243341
Least number k such that k^n - k^(n-1) - k^(n-2) - ... - k^2 - k - 1 is prime.
1
3, 3, 4, 3, 4, 4, 30, 4, 4, 15, 4, 27, 54, 10, 4, 3, 10, 11, 56, 35, 4, 35, 8, 34, 6, 24, 32, 17, 6, 4, 18, 3, 100, 191, 10, 63, 54, 40, 4, 129, 20, 14, 474, 16, 142, 330, 20, 36, 116, 4, 664, 161, 32, 19, 62, 7, 54, 366, 132, 71, 162, 5, 4, 3, 204, 60, 18, 30, 198, 155, 28, 274, 6
OFFSET
1,1
COMMENTS
a(n) > 2 for all n.
LINKS
EXAMPLE
1^1-1 = 0 is not prime. 2^1-1 = 1 is not prime. 3^1-1 = 2 is prime. Thus a(1) = 3.
MATHEMATICA
lnk[n_]:=Module[{k=2}, While[!PrimeQ[k^n-Total[k^Range[0, n-1]]], k++]; k]; Array[lnk, 80] (* Harvey P. Dale, Aug 26 2016 *)
PROG
(PARI) a(n)=for(k=1, oo, if(ispseudoprime(k^n-sum(i=0, n-1, k^i)), return(k)))
for(n=1, 100, print1(a(n)", "))
CROSSREFS
Sequence in context: A167596 A216190 A267592 * A238856 A096139 A175928
KEYWORD
nonn,changed
AUTHOR
Derek Orr, Jun 03 2014
STATUS
approved