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A242516
Numbers n such that k!/n is prime for some k.
1
1, 2, 3, 8, 12, 24, 40, 60, 144, 240, 360, 720, 1008, 1680, 2520, 5760, 8064, 13440, 20160, 51840, 72576, 120960, 181440, 518400, 725760, 1209600, 1814400, 3628800, 5702400, 7983360, 13305600, 19958400, 43545600, 68428800, 95800320, 159667200, 239500800, 479001600, 566092800
OFFSET
1,2
COMMENTS
This sequence is the union of the sequences {n!/p: p | n! and p is prime}. Thus this sequence is infinite.
LINKS
PROG
(PARI)
a(n)=for(k=1, n+2, s=k!/n; if(floor(s)==s, if(ispseudoprime(s), return(k))))
n=1; while(n<10000, if(a(n), print1(n, ", ")); n++)
(PARI)
v=[]; for(n=1, 50, forprime(p=1, n, v=concat(v, n!/p))); vecsort(v) \\ faster program
CROSSREFS
Cf. A242457.
Sequence in context: A303851 A218542 A194452 * A282281 A321175 A079980
KEYWORD
nonn
AUTHOR
Derek Orr, Aug 16 2014
STATUS
approved