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!)
A287956 Numbers k such that k!6 + 6 is prime, where k!6 is the sextuple factorial number (A085158 ). 1
1, 5, 7, 11, 13, 17, 37, 43, 55, 107, 139, 149, 157, 211, 223, 343, 373, 409, 523, 12049, 16457, 17143, 17543, 18391, 25829, 25945, 31307, 34601, 41687 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Corresponding primes are: 7, 11, 13, 61, 97, 941, 49579081, 2131900231, 5745471106381, ...

a(43) > 50000.

Terms > 35 correspond to probable primes.

LINKS

Table of n, a(n) for n=1..29.

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

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

EXAMPLE

11!6 + 6 = 11*5 + 6 = 61 is prime, so 11 is in the sequence.

MATHEMATICA

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

Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 6] + 6] &]

CROSSREFS

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

Sequence in context: A230217 A317250 A007529 * A266266 A246463 A314297

Adjacent sequences:  A287953 A287954 A287955 * A287957 A287958 A287959

KEYWORD

nonn,more

AUTHOR

Robert Price, Jun 03 2017

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 June 21 19:12 EDT 2021. Contains 345365 sequences. (Running on oeis4.)