A074705 - OEIS

%I #5 Jun 13 2016 17:06:09

%S 4,7,11,21,24,31,33,38,74,63,73,101,64,66,126,158,110,122,156,96,136,

%T 181,189,277,252,131,129,129,142,454,453,264,214,348,357,240,368,314,

%U 326,393,271,432,433,221,219,538,942,647,250,248,436,360,528,713,549

%N a(1)=4; for n>1: number of primes between squares of (n-1)-th and (n+1)-th primes.

%H Harvey P. Dale, <a href="/A074705/b074705.txt">Table of n, a(n) for n = 1..1000</a>

%e Primes between A000040(3-1)^2=3*3=9 and A000040(3+1)^2=7*7=49: {11,13,17,19,23,29,31,37,41,43,47}, therefore a(3)=11.

%t Join[{4},Last[#]-First[#]&/@Partition[PrimePi[Prime[Range[60]]^2],3,1]] (* _Harvey P. Dale_, Jun 13 2016 *)

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Sep 03 2002