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

Offset: 1

Author

Daniel Tisdale, Nov 17 2009

Keywords

• nonn

Crossrefs

Cf. A000720, A062298.

Programs

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

Formula

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

Extensions

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

Edited by Jon E. Schoenfield, May 10 2019