A168048 - OEIS

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A168048

a(n) = C(n)*Pi(n) where C(n) = number of nonprimes <= n, Pi(n) = number of primes <= n.

0, 1, 2, 4, 6, 9, 12, 16, 20, 24, 30, 35, 42, 48, 54, 60, 70, 77, 88, 96, 104, 112, 126, 135, 144, 153, 162, 171, 190, 200, 220, 231, 242, 253, 264, 275, 300, 312, 324, 336, 364, 377, 406, 420, 434, 448, 480, 495, 510, 525, 540, 555, 592, 608, 624, 640, 656, 672

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..58.

FORMULA

a(n) = A062298(n)*A000720(n).

MAPLE

A000720 := proc(n) numtheory[pi](n) ; end proc: A168048 := proc(n) pi := A000720(n) ; pi*(n-pi) ; end proc: seq(A168048(n), n=1..120) ; # R. J. Mathar, Nov 18 2009

CROSSREFS

Cf. A000720, A062298.

Sequence in context: A095114 A062048 A194174 * A075354 A194164 A194254

Adjacent sequences: A168045 A168046 A168047 * A168049 A168050 A168051

KEYWORD

nonn

AUTHOR

Daniel Tisdale, Nov 17 2009

EXTENSIONS

a(1) and terms after a(16) from R. J. Mathar, Nov 18 2009

Edited by Jon E. Schoenfield, May 10 2019

STATUS

approved