OFFSET
0,2
COMMENTS
All terms are odd. If the number j is allowed to be 0, then a(1) = 4. - Chai Wah Wu, Mar 24 2022
EXAMPLE
a(4) = 75 because 75 +/- 2^2 = 79 and 71, 75 +/- 2^3 = 83 and 67, 75 +/- 2^5 = 107 and 43, and 75 +/- 2^6 = 139 and 11 are all prime, and 75 is the least number for which there are exactly 4 such powers of 2.
MAPLE
f:= proc(n) local t, s:
nops(select(t -> isprime(n+2^t) and isprime(n-2^t), [$1..ilog2(n)]));
end proc:
V:= Array(0..10): count:= 0:
for n from 1 while count < 11 do
v:= f(n); if V[v] = 0 then V[v] := n; count:= count+1 fi
od:
convert(V, list);
PROG
(Python)
from itertools import count
from sympy import isprime
def A351826(n):
for k in count(1, 2):
c = 0
for j in count(1):
if k-2**j < 2:
break
if isprime(k-2**j) and isprime(k+2**j):
c += 1
if c > n:
break
if c == n: return k # Chai Wah Wu, Mar 24 2022
CROSSREFS
KEYWORD
nonn,more
AUTHOR
J. M. Bergot and Robert Israel, Mar 24 2022
EXTENSIONS
a(11) from Jean-Marc Rebert, Mar 31 2022
STATUS
approved