A171386 The characteristic function of 2 and 3: 1 if n is prime such that either n-1 or n+1 is prime, else 0.

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

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 07 2009

Keywords

• nonn
• easy
• less

Comments

A181354(n) + A181376(n) + A181378(n) + A181380(n) + A181384(n) + A181401(n) + A181403(n) + A181405(n) + a(n) = A052268(n).

Links

• Index entries for linear recurrences with constant coefficients, signature (1).

Crossrefs

Cf. A000007, A010051, A063524.

Programs

Mathematica

Join[{0, 1, 1},LinearRecurrence[{1},{0},102]] (* Ray Chandler, Sep 23 2015 *)

PARI

a(n)=n==2||n==3 \\ Charles R Greathouse IV, Sep 24 2015

Formula

a(n) = A130130(n) - A130130(n-1), for n>0.

Extensions

Edited by Charles R Greathouse IV, Mar 23 2010