A073699 Floor((Product of composite numbers up to n)/(product of primes up to n)).

1, 0, 0, 0, 0, 0, 0, 0, 8, 82, 7, 89, 6, 96, 1450, 23201, 1364, 24565, 1292, 25858, 543035, 11946780, 519425, 12466205, 311655142, 8103033711, 218781910200, 6125893485615, 211237706400, 6337131192016, 204423586839, 6541554778855

Offset

1,9

Comments

Note 1 is neither prime nor composite.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..644

Example

a(10) = Floor((4*6*8*9*10)/(2*3*5*7)) = 82.

Maple

a := 1:b := 1:for i from 2 to 100 do if isprime(i) then a := a*i: else b := b*i:fi: c[i] := floor(b/a):od:c[1] := 1:seq(c[j], j=1..100);

Mathematica

Table[t1 = Select[x = Range[n], PrimeQ]; Floor[Divide @@ Times @@@ {Complement[x, t1], t1}], {n, 32}] (* Jayanta Basu, Jul 06 2013 *)
Module[{upto=40, pr, cm}, pr=Prime[Range[PrimePi[upto]]]; cm=Select[ Range[ upto], CompositeQ]; Table[ Floor[Times@@Select[cm, #<=n&]/ Times@@ Select[ pr, #<=n&]], {n, upto}]] (* Harvey P. Dale, Nov 03 2016 *)

Crossrefs

Sequence in context: A100879 A080811 A249898 * A356829 A358600 A163191

Adjacent sequences: A073696 A073697 A073698 * A073700 A073701 A073702

Keyword

nonn

Author

Amarnath Murthy, Aug 12 2002

Extensions

More terms from Sascha Kurz, Aug 15 2002

Status

approved