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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A046683 Sum of squares of divisors of n and sum of cubes of divisors of n are relatively prime. 7
1, 2, 4, 9, 18, 25, 36, 100, 121, 225, 289, 484, 529, 841, 900, 1089, 1156, 1681, 2116, 2209, 2601, 2809, 3364, 3481, 4356, 4761, 5041, 6724, 6889, 7225, 7569, 7921, 8836, 10201, 10404, 11236, 11449, 12769, 13225, 13924, 15129, 17161, 18769, 19044 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It can be shown that this is a subset of A028982.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

sdcdQ[n_]:=Module[{d=Divisors[n]}, CoprimeQ[Total[d^2], Total[d^3]]]; Select[ Range[ 20000], sdcdQ] (* Harvey P. Dale, Apr 09 2018 *)

PROG

(PARI) isok(n) = gcd(sigma(n, 2), sigma(n, 3)) == 1; \\ Michel Marcus, Sep 24 2019

CROSSREFS

Cf. A028982, A046678, A046679, A046680, A046681, A046685.

Sequence in context: A321736 A024425 A034685 * A065055 A065030 A103321

Adjacent sequences:  A046680 A046681 A046682 * A046684 A046685 A046686

KEYWORD

nonn

AUTHOR

Labos Elemer

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 November 13 02:59 EST 2019. Contains 329085 sequences. (Running on oeis4.)