OFFSET
1,3
EXAMPLE
a(3)=2 since for the third prime 5 we have 5*2-(5+2)=3 and 5*3-(5+3)=7. Also a(4)=3 since for the fourth prime 7 we have 7*2-(7+2)=5, 7*3-(7+3)=11 and 7*5-(7+5)=23.
MATHEMATICA
Table[p = Prime[n]; c = 0; i = 1; While[i < n, If[PrimeQ[p*Prime[i] - (p + Prime[i])], c = c + 1] i++]; c, {n, 75}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Jayanta Basu, Apr 20 2013
STATUS
approved