login
A076557
Greatest prime divisor of (n-th prime - n).
1
2, 3, 3, 7, 5, 11, 7, 19, 5, 5, 7, 29, 2, 37, 7, 43, 3, 17, 13, 19, 5, 13, 3, 5, 19, 79, 5, 83, 3, 11, 13, 7, 19, 23, 5, 5, 2, 19, 23, 139, 37, 149, 19, 17, 41, 7, 89, 179, 13, 17, 47, 197, 101, 23, 53, 71, 109, 17, 37, 11, 61, 19, 31, 251, 11, 269, 139, 31, 47, 41, 7, 23, 19
OFFSET
3,1
LINKS
FORMULA
a(n) = A006530(A014689(n)). - Michel Marcus, Feb 15 2014
EXAMPLE
a(3) = 2, since the greatest prime divisor of prime(3) - 3 = 5 - 3 = 2 is 2.
MATHEMATICA
nn=80; Drop[FactorInteger[#][[-1, 1]]&/@(First[#]-Last[#]&/@Thread[ {Prime[Range[nn]], Range[nn]}]), 2] (* Harvey P. Dale, Jun 21 2011 *)
CROSSREFS
Sequence in context: A079387 A141061 A256447 * A228548 A140407 A063670
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Oct 19 2002
STATUS
approved