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A071260 Integer part of the geometric mean of the n-th prime prime(n) and the n-th composite number C(n). 2
2, 4, 6, 7, 10, 12, 15, 16, 19, 22, 24, 27, 30, 32, 34, 37, 39, 41, 44, 47, 49, 51, 53, 56, 60, 62, 64, 67, 69, 71, 76, 79, 81, 83, 87, 88, 92, 94, 96, 99, 101, 104, 108, 110, 112, 113, 118, 123, 125, 126, 129, 132, 134, 138, 140, 143, 146, 148, 150, 153, 155, 158 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

FORMULA

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

EXAMPLE

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

MATHEMATICA

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 *)

CROSSREFS

Cf. A071259.

Sequence in context: A047510 A189030 A198033 * A026407 A003035 A094453

Adjacent sequences:  A071257 A071258 A071259 * A071261 A071262 A071263

KEYWORD

nonn

AUTHOR

Amarnath Murthy, May 30 2002

EXTENSIONS

More terms from Hans Havermann, Sep 23 2002

STATUS

approved

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Last modified November 22 08:46 EST 2019. Contains 329389 sequences. (Running on oeis4.)