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A229271
Numbers n for which n + n' and n - n' are both prime, n' being the arithmetic derivative of n.
3
10, 14, 15, 21, 26, 33, 35, 38, 51, 65, 66, 78, 86, 93, 102, 110, 111, 123, 161, 201, 203, 206, 209, 215, 221, 230, 258, 278, 282, 321, 371, 374, 395, 398, 402, 413, 438, 470, 471, 485, 530, 533, 543, 545, 551, 590, 626, 671, 678, 698, 723, 755, 779, 803, 815
OFFSET
1,1
COMMENTS
Intersection of A165561 and A229269.
LINKS
MAPLE
with(numtheory); P:=proc(q) local a, n, p; for n from 1 to q do
a:=n*add(op(2, p)/op(1, p), p=ifactors(n)[2]);
if isprime(n+a) and isprime(n-a) then print(n); fi;
od; end: P(10^5);
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Sep 18 2013
STATUS
approved