A082551 Denote sigma(n)-n by s(n); a(n)=1 if s(n)>n, a(n)=0 if s(n)=n, a(n)=-1 if s(n)<n.

-1, -1, -1, -1, -1, 0, -1, -1, -1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 0, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Formula

a(n) = sign(A033880(n)).

Maple

A082551 := proc(n)
        signum( numtheory[sigma](n)-2*n) ;
end proc: # R. J. Mathar, Sep 28 2011

Mathematica

Table[Sign[DivisorSigma[1, n] - 2*n], {n, 1, 100}] (* Amiram Eldar, Mar 15 2024 *)

Prog

(PARI) A082551(n) = sign(sigma(n)-(2*n)); \\ Antti Karttunen, Sep 28 2018

Crossrefs

Cf. A000203, A001065, A033879, A033880, A060862, A294934, A294935, A294936, A294937.

Sequence in context: A380545 A300294 A071041 * A380484 A152614 A127507

Adjacent sequences: A082548 A082549 A082550 * A082552 A082553 A082554

Keyword

easy,sign

Author

Hanoch M. bin (hanochb(AT)shiron.com), May 12 2003

Status

approved