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A357369
a(n) is the first prime p such that (p+q)/(2*n) is prime, where q is the next prime after p.
2
3, 5, 11, 13, 11, 19, 53, 17, 29, 467, 59, 23, 41, 29, 173, 31, 197, 4877, 59, 41, 151, 67, 71, 47, 751, 79, 53, 661, 59, 89, 61, 97, 101, 103, 71, 109, 73, 193, 113, 199, 461, 83, 1361, 223, 137, 3331, 139, 2297, 149, 101, 257, 1531, 107, 163, 1621, 397, 751, 997, 113, 7741, 181, 313, 191, 193
OFFSET
2,1
LINKS
EXAMPLE
a(4) = 11 because (11+13)/(2*4) = 3 is prime, and no smaller prime works.
MAPLE
V:= Vector(100): count:= 0:
q:= 3:
while count < 99 do
p:= q; q:= nextprime(q);
m:= (p+q)/2;
for r in numtheory:-factorset(m) do
v:= m/r;
if v <= 100 and V[v] = 0 then
count:= count+1; V[v]:= p;
fi
od
od:
convert(V[2..100], list);
CROSSREFS
Cf. A357373.
Sequence in context: A309426 A115398 A014597 * A130603 A069977 A284795
KEYWORD
nonn
AUTHOR
Robert Israel, Sep 25 2022
STATUS
approved