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!)
A071312 Squarefree numbers such that the largest prime factor = sum of other prime factors. 0
30, 70, 286, 646, 1798, 3135, 3526, 3570, 6279, 7198, 8855, 8970, 10366, 10626, 10695, 11571, 16095, 16530, 17255, 17391, 20615, 20706, 20735, 20806, 23326, 24738, 24882, 26691, 28083, 31031, 36519, 36890, 38086, 38130, 41151, 41615 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If n = p(1)*p(2)*...p(r) is in the sequence, where p(r) is the largest prime factor, then p(r) = p(1)+p(2)+...+p(r-1)

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

20706 = 2.3.7.17.29 and 2+3+7+17 = 29 hence 20706 is in the sequence

PROG

(PARI) for(n=2, 100000, if(issquarefree(n)*sum(i=1, omega(n)-1, component(component(factor(n), 1), i))==vecmax(factor(n, 1)), print1(n, ", ")))

CROSSREFS

Cf. A071141.

Sequence in context: A131647 A301900 A071141 * A071142 A218327 A259753

Adjacent sequences:  A071309 A071310 A071311 * A071313 A071314 A071315

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Jun 11 2002

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 24 11:17 EDT 2021. Contains 346273 sequences. (Running on oeis4.)