A171387 The characteristic function of primes > 3: 1 if n is prime such that neither prime+-1 is prime else 0.

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

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 07 2009

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..1001
• Index entries for characteristic functions

Crossrefs

Cf. A000007, A010051, A063524, A080545, A169546, A171386.

Formula

A010051(n) = a(n) + A171386(n).

If n > 3, a(n) = A010051(n), otherwise a(n) = 0. - Antti Karttunen, Oct 04 2017