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

1,1

Comments

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

Links

Table of n, a(n) for n=1..105.

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

Formula

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

Mathematica

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

Prog

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

Crossrefs

Cf. A000007, A010051, A063524.

Sequence in context: A358224 A072608 A295304 * A189816 A342000 A194685

Adjacent sequences: A171383 A171384 A171385 * A171387 A171388 A171389

Keyword

nonn,easy,less

Author

Juri-Stepan Gerasimov, Dec 07 2009

Extensions

Edited by Charles R Greathouse IV, Mar 23 2010

Status

approved