a(n) can be thought of as the radius of the largest 1-dimensional circle centered at Prime(n) and consisting entirely of primes.
Table of n, a(n) for n=0..9.
r = 4 is the largest nonnegative integer r such that Prime(4) + 4 = 11 and
Prime(4) - 4 = 3 are both prime; so a(4) = 4.
Sequence in context: A190751 A030232 A102024 * A189792 A189782 A047235
Adjacent sequences: A104194 A104195 A104196 * A104198 A104199 A104200
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Mar 12 2005