A071260 - OEIS

%I #9 Aug 12 2016 18:23:01

%S 2,4,6,7,10,12,15,16,19,22,24,27,30,32,34,37,39,41,44,47,49,51,53,56,

%T 60,62,64,67,69,71,76,79,81,83,87,88,92,94,96,99,101,104,108,110,112,

%U 113,118,123,125,126,129,132,134,138,140,143,146,148,150,153,155,158

%N Integer part of the geometric mean of the n-th prime prime(n) and the n-th composite number C(n).

%H Harvey P. Dale, <a href="/A071260/b071260.txt">Table of n, a(n) for n = 0..1000</a>

%F Floor [ {prime(n)* C(n)}^(1/2)]

%e a(7) =floor {prime(7)*C(7)}^(1/2) = (17*14)^1/2 = 15.

%t Module[{nn=100,prs,cmps,len},prs=Prime[Range[nn]];cmps=Select[ Range[ nn+Length[prs]],CompositeQ];len=Min[Length[cmps],Length[prs]];IntegerPart[ GeometricMean[#]]&/@Thread[{Take[prs,len],Take[ cmps,len]}]] (* _Harvey P. Dale_, Aug 12 2016 *)

%Y Cf. A071259.

%K nonn

%O 0,1

%A _Amarnath Murthy_, May 30 2002

%E More terms from _Hans Havermann_, Sep 23 2002