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!)
A213386 Smallest number k such that the sum of the distinct prime divisors of k equals n times a square > 1. 5
14, 15, 35, 39, 51, 95, 115, 87, 155, 111, 123, 215, 235, 159, 371, 183, 302, 335, 219, 511, 395, 415, 267, 623, 291, 303, 482, 327, 339, 791, 554, 1415, 635, 655, 411, 695, 662, 447, 698, 471, 734, 815, 835, 519, 1211, 543, 842, 1991, 579, 591, 914, 2167 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Smallest k such that sopf(k) = n*q where q is a square.

LINKS

Michel Lagneau, Table of n, a(n) for n = 1..1000

EXAMPLE

a(55) = 2631 because 2631 = 3*877 and 3 + 877 = 880 = 55*16 where 16 is a square.

MAPLE

with (numtheory):

sopf:= proc(n) option remember;

add(i, i=factorset(n))

end:

a:= proc(n) local k, p;

for k from 2 while irem(sopf(k), n, 'p')>0 or

sqrt(p)<>floor(sqrt(p)) or p=1 do od; k

end:

seq (a(n), n=1..100);

CROSSREFS

Cf. A008492, A213420.

Sequence in context: A162283 A180328 A211144 * A041404 A041402 A041929

Adjacent sequences:  A213383 A213384 A213385 * A213387 A213388 A213389

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jun 10 2012

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 26 03:19 EDT 2021. Contains 347664 sequences. (Running on oeis4.)