

A289696


Numbers k such that k!6  18 is prime, where k!6 is the sextuple factorial number (A085158).


1



11, 13, 23, 25, 35, 85, 89, 91, 103, 127, 161, 265, 295, 385, 605, 719, 913, 1379, 1423, 1481, 1603, 2129, 2603, 3893, 4739, 6461, 7249, 7549, 8149, 10633, 14447, 27463, 30323, 33991, 35821, 42221, 46525, 59057
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OFFSET

1,1


COMMENTS

Corresponding primes are: 37, 73, 21487, 43207, 21827557, 11510631741140058401857, ...
a(39) > 10^5.
Terms > 35 correspond to probable primes.


LINKS



EXAMPLE

13!6  18 = 13*7  18 = 73 is prime, so 13 is in the sequence.


MATHEMATICA

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n  k, k]];
Select[Range[9, 50000], PrimeQ[MultiFactorial[#, 6]  18] &]
Select[Range[11, 60000], PrimeQ[Times@@Range[#, 1, 6]18]&] (* Harvey P. Dale, Aug 10 2019 *)


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



