OFFSET
1,3
COMMENTS
a(n) is prime for n = {3,4,5,6,7,31,738}; a(738) ~ 7.1 * 10^18518. There are no others for n up to 1000. - Peter J. C. Moses, Mar 03 2014
EXAMPLE
Let n=4, prime(n)=7. Consider integers i!+6!/i!, i=1,2,3,4,5: 721,362,126,54,126. Among them 721,126,126 are divisible by 7. So a(4)=(721 + 126 + 126)/7 = 139.
MATHEMATICA
Map[Total[Cases[Table[i!+(#-1)!/i!, {i, #-2}]/#, _Integer]]&, Prime[Range[10]]] (* Peter J. C. Moses, Mar 10 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev and Peter J. C. Moses, Mar 03 2014
STATUS
approved