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A139689 If (n-th Chen prime) + 2 is a prime then 1 else 0. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..1000

Index entries for characteristic functions

Eric Weisstein's World of Mathematics, Chen Prime

FORMULA

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

CROSSREFS

Sequence in context: A010051 A131929 A100821 * A073070 A099104 A066829

Adjacent sequences:  A139686 A139687 A139688 * A139690 A139691 A139692

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Apr 29 2008

STATUS

approved

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Last modified January 20 10:23 EST 2018. Contains 297960 sequences.