

A085274


Composite k such that (k!/k#) + 1 is a semiprime, where k# = primorial numbers A034386.


0



6, 10, 21, 22, 24, 25, 27, 30, 39, 48, 52, 57, 65, 87, 94, 110, 114, 124, 156, 161
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OFFSET

1,1


COMMENTS

n!/n# is called n compositorial. The actual sequence is (6,7),(10,11),21,(22,23),24,25,27,(30,31),39,48, (52,53),57,65,... where the values in parenthesis yield the same semiprime.
That is, since p!/p# = (p1)!/(p1)#, primes never appear in this sequence.  Sean A. Irvine, Jun 30 2020


LINKS



EXAMPLE

25!/25# + 1 is a product of two primes: 69528040243200001 = 2594807 * 26795071943.


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



