OFFSET
1,1
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..300
EXAMPLE
n=7: a(7)=7, 7!=5040, 7.7!=35280 and {35279,35281} are primes.
MATHEMATICA
Table[fl=1; Do[s=(j!)*k; If[PrimeQ[s-1]&&PrimeQ[s+1]&&Equal[fl, 1], Print[{j, k}]; fl=0], {k, 1, 2*j^2}], {j, 0, 100}]
smnf[n_]:=Module[{k=1, f=n!}, While[!PrimeQ[k*f+1]||!PrimeQ[k*f-1], k++]; k]; Array[smnf, 60] (* Harvey P. Dale, May 24 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 24 2002
STATUS
approved