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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A247465 Numbers n such that n!3 - 3^5 is prime. 1
10, 19, 28, 50, 67, 77, 89, 112, 139, 146, 184, 194, 233, 310, 311, 388, 886, 1139, 1648, 1694, 2405, 2554, 3709, 4015, 5410, 5908, 6407, 8065, 9061, 9875, 11722, 13471, 26026, 26656, 29441, 32741 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Large terms correspond to probable primes.

a(37) > 50000.

LINKS

Table of n, a(n) for n=1..36.

Henri & Renaud Lifchitz, PRP Records. Search for n!3-243

Joe McLean, Interesting Sources of Probable Primes

OpenPFGW Project, Primality Tester

Eric Weisstein's World of Mathematics, Multifactorial

EXAMPLE

10!3-243 = 10*7*4*1-243 = 37 is prime, so 10 is in the sequence.

MATHEMATICA

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

lst={}; Do[If[PrimeQ[MultiFactorial[n, 3] - 243], AppendTo[lst, n]], {n, 100}]; lst

CROSSREFS

Cf. A007661, A037082, A084438, A243078.

Sequence in context: A017173 A326833 A276871 * A088410 A179110 A126624

Adjacent sequences:  A247462 A247463 A247464 * A247466 A247467 A247468

KEYWORD

nonn,more

AUTHOR

Robert Price, Sep 17 2014

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 October 21 14:40 EDT 2019. Contains 328301 sequences. (Running on oeis4.)