A109559 - OEIS

%I #2 Mar 30 2012 17:34:19

%S 23,31,283,337,409,421,547,577,631,661,797,997,1201,1237,1307,1459,

%T 1499,1511,1531,1583,1709,1789,1811,1889,2039,2357,2423,2633

%N a(n) = If[Floor[2*Mod[(Prime[n + 1] - Prime[n])*PrimePi[n]/n, 8]] == 5, Prime[n]]

%t a = Flatten[Table[If[Floor[2*Mod[(Prime[n + 1] - Prime[n])*PrimePi[n]/n, 8]] == 5, Prime[n], {}], {n, 1, 400}]]

%Y Cf. A001359.

%K nonn

%O 0,1

%A _Roger L. Bagula_, Jun 27 2005