OFFSET
1,1
COMMENTS
Primes of the form p^k - k where p is prime are 2, 5, 7, 23, 47, 167, 359, 503, ...
Subsequence of A057897.
A182474 is a subsequence.
Up to 10^14 all the terms have a unique representation as p^k - k. - Giovanni Resta, Mar 21 2017
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
2 is a term because 2 = 2^2 - 2.
5 is a term because 5 = 2^3 - 3.
7 is a term because 7 = 3^2 - 2.
12 is a term because 12 = 2^4 - 4.
121 is a term because 121 = 2^7 - 7.
MAPLE
N:= 10000: # to get all terms <= N
P:= select(isprime, [$1..floor((N+2)^(1/2))]):
S:= {}:
for k from 2 do
pmax:= floor((N+k)^(1/k));
if pmax < 2 then break fi;
S:= S union {seq(p^k-k, p = select(`<=`, P, pmax))};
od:
sort(convert(S, list)); # Robert Israel, Mar 21 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Altug Alkan, Mar 04 2016
STATUS
approved