OFFSET
1,35
COMMENTS
a(n) < A020639(n). - Robert Israel, Aug 12 2014
LINKS
Jens Kruse Andersen, Table of n, a(n) for n = 1..10000
MAPLE
a:= n -> nops(select(k -> isprime(n+k!) and isprime(n-k!),
[$1 ..min(numtheory:-factorset(n))-1])):
0, seq(a(n), n=2..100); # Robert Israel, Aug 12 2014
PROG
(PARI)
a(n)=c=0; for(k=1, n, if(ispseudoprime(n+k!)&&ispseudoprime(n-k!), c++)); return(c)
vector(100, n, a(n))
CROSSREFS
KEYWORD
nonn
AUTHOR
Derek Orr, Aug 12 2014
STATUS
approved