OFFSET
0,1
COMMENTS
All terms are primes.
a(n) = 2 for n = {1,2,4,5,7,8,10,13,14,17,19,20,22,...} = A067076 Numbers n such that 2n+3 is a prime.
a(34),...,a(40) = {2,2,3,3,2,29,2}.
a(42),...,a(80) = {167,2,7,3,3,2,61,2,2,11,2,2,157,2,5,7,7,149,3,5,2,379,2,41,3,2,2,3,79,11,3,2,2,97,3,2,3,3,2}.
a(82),...,a(90) = {2,17,31,2,61,7,2,2,5}.
a(93),...,a(95) = {383,2,2}.
a(97),...,a(100) = {2,2,5,7}.
a(102),...,a(124) = {13,11,2,5,5,17,3,103,2,19,2,2,3,2,31,37,2,2,3,3,7,3,2}.
a(127),...,a(131) = {2,61,31,2,157}.
a(133),...,a(142) = {2,2,7,3,2,13,2,2,7,3}.
a(144),...,a(146) = {173,2,11}.
a(148),...,a(150) = {3,17,107}.
a(n) is currently unknown for n = {33,41,81,91,92,96,101,125,126,132,143,147,...}.
MATHEMATICA
Do[k = 1; While[ !PrimeQ[((2n+1)^k - 2^k)/(2n-1)], k++ ]; Print[k], {n, 100}] (* Ryan Propper, Mar 29 2007 *)
lnk[n_]:=Module[{k=1}, While[!PrimeQ[((2n+1)^k-2^k)/(2n-1)], k++]; k]; Array[ lnk, 90] (* Harvey P. Dale, May 19 2012 *)
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Alexander Adamchuk, Feb 07 2007
EXTENSIONS
More terms from Ryan Propper, Mar 29 2007
STATUS
approved