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A365475
a(n) is the first odd prime p such that A000120((2^n-1)*p) = n * A000120(p).
3
3, 5, 17, 17, 257, 257, 257, 257, 65537, 65537, 65537, 65537, 65537, 65537, 65537, 65537, 4398054899713, 4398054899713, 4398054899713, 1125899915231233, 1125899915231233, 1125899915231233, 1125899915231233, 2251799847239681, 2251799847239681, 1152921513196781569, 1152921513196781569
OFFSET
1,1
COMMENTS
a(n) is the first odd prime p such that between any two 1's in the base-2 representation of p there are at least n-1 0's.
LINKS
EXAMPLE
a(3) = 17 because A000120((2^3-1) * 17) = A000120(119) = 6 = 3 * A000120(17).
MAPLE
f:= proc(m) local S, d, j, r, q;
S[0]:= [1];
for d from 1 do
S[d]:= NULL;
for j from 0 to d-m do
for r in S[j] do
q:= r + 2^d;
if isprime(q) then return q fi;
S[d]:= S[d], q;
od;
od;
S[d]:= [S[d]];
od;
end proc:
map(f, [$1..30]);
CROSSREFS
Cf. A000120.
Sequence in context: A292008 A139427 A360802 * A191051 A040129 A045415
KEYWORD
nonn,base
AUTHOR
Robert Israel, Sep 04 2023
STATUS
approved