login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A267029 Numbers n such that n!!! - 3^9 is prime, where n!3 = n!!! is a triple factorial number (A007661). 1
16, 17, 34, 38, 49, 62, 74, 97, 125, 137, 146, 178, 188, 235, 664, 863, 916, 1988, 2059, 2837, 5353, 5489, 7483, 9344, 12631, 13796, 17122, 23134, 30409, 33077 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding primes are 38557, 189757, 17961239276317, 3091650738156317, ... .

a(31) > 50000.

LINKS

Table of n, a(n) for n=1..30.

Henri & Renaud Lifchitz, PRP Records. Search for n!3-19683.

Joe McLean, Interesting Sources of Probable Primes

EXAMPLE

16!3 - 3^9 = 16*13*10*7*4*1 - 19683 = 58240 - 19683 = 38557 is prime, so 16 is in the sequence.

MATHEMATICA

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

Select[Range[15, 50000], PrimeQ[MultiFactorial[#, 3] - 3^9] &]

CROSSREFS

Cf. A006882, A007749, A094144, A123910, A258452, A258616, A262772, A261145, A265201.

Sequence in context: A041516 A041514 A041512 * A070869 A101196 A064637

Adjacent sequences:  A267026 A267027 A267028 * A267030 A267031 A267032

KEYWORD

hard,more,nonn

AUTHOR

Robert Price, Jan 09 2016

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 24 19:42 EDT 2019. Contains 321448 sequences. (Running on oeis4.)