This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A079261 Characteristic function of primes of form 4n+3 (1 if n is prime of form 4n+3, 0 otherwise). 10

%I

%S 0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,

%T 0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,

%U 0,0,1,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0

%N Characteristic function of primes of form 4n+3 (1 if n is prime of form 4n+3, 0 otherwise).

%C Let M(n) denote the n X n matrix m(i,j)=0 if n divides ij-1, m(i,j) = 1 otherwise then det(M(n))=+1 if and only if n is prime ==3 (mod 4).

%C a(A002145(n)) = 1; a(A145395(n)) = 0. [From _Reinhard Zumkeller_, Oct 12 2008]

%C a(n) * A151763(n) = - a(n).

%H Reinhard Zumkeller, <a href="/A079261/b079261.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F a(n) = - A010051(n) * A011764(n+1). [_Reinhard Zumkeller_, Oct 06 2011]

%o (PARI) { a(n)=isprime(n)*if(n%4-3,0,1) }; vector(100,n,a(n))

%o a079261 n = fromEnum \$ n `mod` 4 == 3 && a010051 n == 1

%o -- _Reinhard Zumkeller_, Oct 06 2011

%Y Cf. A002145, A079260.

%Y Cf. A066490 (partial sums).

%K nonn

%O 1,1

%A _Benoit Cloitre_, Feb 04 2003

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 20 16:20 EST 2019. Contains 319335 sequences. (Running on oeis4.)