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A161562 Even numbers n such that { n-p ; p prime, 2 < p < n/2 } contains at least twice as much primes than composites. 0
2, 4, 6, 8, 10, 16, 18, 20, 22, 24, 36, 60, 84, 90, 114, 120, 210, 420 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It seems that this sequence is finite, and that 420 is the largest term. [M. F. Hasler, Nov 11 2009]

LINKS

Table of n, a(n) for n=1..18.

EXAMPLE

16-3=13,16-5=11.(primes:2 times) 16-7=9.(composite:1 time);

24-5=19,24-7=17,24-11=13.(primes:3 times) 24-3=21.(composite:1 time);

90-3=87,90-7=83,90-11=79,90-17=73,90-19-71,90-23=67,90-29=61,90-31=59,90-37=53,90-43=47.(primes:10 times) 90-5=85,90-13=77,90-41=49.(composite:3 times),..

PROG

(PARI) {for(n=1, 1e6, my(s=0); forprime( p=3, n-1, s+=if( isprime(2*n-p), 1, -2)); s>=0 & print1(2*n", "))} \\ M. F. Hasler, Nov 11 2009

CROSSREFS

Sequence in context: A177867 A338738 A226809 * A333019 A102470 A057195

Adjacent sequences:  A161559 A161560 A161561 * A161563 A161564 A161565

KEYWORD

nonn,fini,full

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jun 13 2009

EXTENSIONS

Reworded definition and initial terms added by M. F. Hasler, Nov 11 2009

STATUS

approved

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Last modified May 7 08:12 EDT 2021. Contains 343636 sequences. (Running on oeis4.)