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%I #11 Mar 25 2019 03:50:51
%S 0,0,2,4,8,10,14,12,20,24,28,34,38,40,42,50,54,48,64,68,66,72,80,84,
%T 94,98,96,104,102,110,124,126,134,132,144,132,154,150,164,144,174,178,
%U 188,190,192,180,208,220,222,210,230,228,238,248,252,260,252,252,270
%N Largest nonnegative integer r such that prime(n) + r and prime(n) - r are both prime.
%C a(n) can be thought of as the radius of the largest 1-dimensional circle centered at prime(n) and consisting entirely of primes.
%H Amiram Eldar, <a href="/A104197/b104197.txt">Table of n, a(n) for n = 1..10000</a>
%e 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.
%t a[p_] := Module[{k = p-3}, While[!PrimeQ[p+k] || !PrimeQ[p-k], k-=2]; k]; Join[{0}, a/@Select[Range[3, 1000], PrimeQ]] (* _Amiram Eldar_, Mar 24 2019 *)
%K easy,nonn
%O 1,3
%A _Joseph L. Pe_, Mar 12 2005
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