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!)
A300572 Numbers k such that k and the sum of the divisors of k have the same prime signature. 2
1, 2, 12, 52, 75, 90, 98, 150, 338, 528, 560, 722, 867, 912, 1452, 1456, 1525, 1734, 1922, 2064, 2340, 2890, 3050, 3120, 3216, 3698, 4144, 4950, 5043, 6348, 6516, 6804, 7350, 7824, 8176, 8880, 9024, 9920, 10086, 10128, 10304, 10443, 10658, 11340, 11858, 13584 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

2 is the only prime. - Michel Marcus, Mar 10 2018

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..3000

FORMULA

{ k | A046523(k) = A046523(A000203(k)) }.

MAPLE

s:= n-> sort(map(i-> i[2], ifactors(n)[2])):

a:= proc(n) option remember; local k; for k from 1+

      a(n-1) while s(k)<>s(numtheory[sigma](k)) do od; k

    end: a(0):=0:

seq(a(n), n=1..60);

PROG

(PARI) isok(k) = vecsort(factor(k)[, 2]) == vecsort(factor(sigma(k))[, 2]); \\ Michel Marcus, Mar 10 2018

CROSSREFS

Cf. A000203, A008578, A046523, A300216, A300573.

Sequence in context: A057547 A216648 A043007 * A176580 A179259 A261474

Adjacent sequences:  A300569 A300570 A300571 * A300573 A300574 A300575

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Mar 08 2018

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 September 17 12:00 EDT 2021. Contains 347477 sequences. (Running on oeis4.)