A139689 If (n-th Chen prime) + 2 is a prime then 1 else 0.

0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0

Offset: 1

Author

Reinhard Zumkeller, Apr 29 2008

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
• Eric Weisstein's World of Mathematics, Chen Prime
• Index entries for characteristic functions

Crossrefs

Cf. A001222, A010051, A064911, A139690.

Formula

a(n) = 2 - A001222(A139690(n)).

a(n) = A010051(A139690(n)) = 1 - A064911(A139690(n)).