login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A296211 a(n) = 1 if sigma(n)-1 is a prime, 0 otherwise. 3
0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

COMMENTS

Characteristic function of A248792, numbers n such that sigma(n) - 1 is a prime.

LINKS

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

Index entries for characteristic functions

FORMULA

a(1) = 0; for n > 1, a(n) = A010051(A000203(n)-1) = A010051(A039653(n)).

a(n) >= A010051(n).

PROG

(Scheme) (define (A296211 n) (if (= 1 n) 0 (A010051 (+ -1 (A000203 n)))))

CROSSREFS

Cf. A000203, A010051, A039653, A248792 (positions of ones), A296091, A296212.

Sequence in context: A288861 A030190 A157658 * A123506 A051105 A284929

Adjacent sequences:  A296208 A296209 A296210 * A296212 A296213 A296214

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 07 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 October 16 05:23 EDT 2019. Contains 328043 sequences. (Running on oeis4.)