login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A289698 Numbers k such that k!6 - 27 is prime, where k!6 is the sextuple factorial number (A085158). 1
10, 14, 16, 34, 46, 86, 116, 130, 344, 410, 446, 746, 824, 1580, 1682, 1918, 2684, 2710, 4172, 4754, 6976, 7418, 8788, 11756, 13546, 16048, 17192, 19624, 24026, 28510, 32758, 41780, 42740, 45856, 51050 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding primes are: 13, 197, 613, 13404133, 24663654373, 37455569511954513919973, ...

a(36) > 10^5.

Terms > 46 correspond to probable primes.

LINKS

Table of n, a(n) for n=1..35.

Henri & Renaud Lifchitz, PRP Records. Search for n!6-27.

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

EXAMPLE

14!6 - 27 = 14*8*2 - 27 = 197 is prime, so 14 is in the sequence.

MATHEMATICA

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];

Select[Range[10, 50000], PrimeQ[MultiFactorial[#, 6] - 27] &]

CROSSREFS

Cf. A007661, A037082, A084438, A123910, A242994.

Sequence in context: A213310 A055197 A116610 * A153041 A256471 A250403

Adjacent sequences:  A289695 A289696 A289697 * A289699 A289700 A289701

KEYWORD

nonn,more

AUTHOR

Robert Price, Jul 09 2017

EXTENSIONS

a(35) from Robert Price, Aug 04 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 31 16:23 EDT 2020. Contains 333151 sequences. (Running on oeis4.)