login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A296084 a(1) = 0 and for n > 1, a(n) = 1 if tau(n)-1 divides sigma(n)-1, 0 otherwise. Here tau = A000005, sigma = A000203. 5
0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

COMMENTS

Also number of numbers of the form i*n with 1 <= i <= n and tau(i*n) = 3 (equivalently, i*n is the square of a prime). - N. J. A. Sloane, Nov 11 2020

LINKS

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

Index entries for characteristic functions

FORMULA

a(n) = 1 iff A296082(n) = 1.

MATHEMATICA

Join[{0}, Table[If[Divisible[DivisorSigma[1, n]-1, DivisorSigma[0, n]-1], 1, 0], {n, 2, 120}]] (* Harvey P. Dale, Dec 15 2018 *)

PROG

(PARI) A296084(n) = if(1==n, 0, !((sigma(n)-1)%(numdiv(n)-1)));

CROSSREFS

Cf. A000005, A000203, A032741, A039653, A296082.

Characteristic function of A284288.

Sequence in context: A100656 A285274 A189081 * A302777 A324828 A053867

Adjacent sequences:  A296081 A296082 A296083 * A296085 A296086 A296087

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 05 2017

STATUS

approved

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 30 19:33 EDT 2021. Contains 346359 sequences. (Running on oeis4.)