OFFSET
1,1
COMMENTS
It seems that this sequence is finite, and that 420 is the largest term. [M. F. Hasler, Nov 11 2009]
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
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
Definition reworded by Harvey P. Dale, Sep 17 2023
STATUS
approved