



7, 17, 50, 71, 449, 851, 881, 1467, 2591, 5123, 9521, 18167, 29817, 34859, 38027, 39761, 52415, 84359, 90611, 92711, 106721, 147267, 179999, 204479, 206081, 342791, 388961, 596231, 606609, 847601, 922607, 1060307, 1256879, 1292831, 1389671, 1590983, 1976015, 2157227, 2169971, 2268449, 2571911
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OFFSET

1,1


COMMENTS

Numbers k such that k + A000203(k) is the product of a twin prime pair.


LINKS



EXAMPLE

a(3) = 50 is a term because 50 + A000203(50) = 143 = 11*13 where (11,13) is a twin prime pair.


MAPLE

filter:= proc(n) local t, s; t:= n + numtheory:sigma(n);
if t::even or not issqr(t+1) then return false fi;
s:= sqrt(t+1);
isprime(s+1) and isprime(s1)
end proc:
select(filter, [$1..3000000]);


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



