A370010 - OEIS

%I #9 Feb 16 2024 15:08:27

%S 7,11,19,23,43,47,67,73,89,113,113,139,163,167,181,211,233,241,263,

%T 283,283,313,331,353,383,401,409,421,433,449,503,523,547,547,593,601,

%U 619,647,661,691,709,719,761,769,787,787,839,887,907,911,929,953,953,997

%N a(n) is the greatest prime less than 4*prime(n).

%e 7 < 4*2 < 11 < 4*3 < 13 < 17 < 19  < 5*3 < 23, so (a(1), a(2), a(3)) = (7,11,19).

%t Table[Prime[PrimePi[4*Prime[n]]], {n,1,200}]

%o (PARI) a(n) = precprime(4*prime(n)); \\ _Michel Marcus_, Feb 10 2024

%Y Cf. A000040, A001749, A059786, A059788, A370008, A370011.

%K nonn

%O 1,1

%A _Clark Kimberling_, Feb 09 2024