This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A085056 (Product of all composite numbers from 1 to n)/ ( product of the prime divisors of all composite numbers up to n). More precisely, denominator = product of the largest squarefree divisors of composite numbers up to n. 4
 1, 1, 1, 2, 2, 2, 2, 8, 24, 24, 24, 48, 48, 48, 48, 384, 384, 1152, 1152, 2304, 2304, 2304, 2304, 9216, 46080, 46080, 414720, 829440, 829440, 829440, 829440, 13271040, 13271040, 13271040, 13271040, 79626240, 79626240, 79626240, 79626240 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..200 FORMULA a(1)=1, a(n)=a(n-1)*n/(n's prime factors). a(1) = 1, a(n+1) = a(n)*{(n)/(the largest squarefree divisor of n)}. - Amarnath Murthy, Nov 28 2004 a(n) = prod_{i=1..n} A003557(i). - Tom Edgar, Mar 24 2014 EXAMPLE a(9) = (4*6*8*9)/((2)*(2*3)*(2)*(3)) = 24. MAPLE A085056 := proc(n) local S, i; S := A003557(n); for i from 2 to n do S[i] := S[i] * S[i-1]; od; S end: # Peter Luschny, Jun 29 2009 MATHEMATICA PrimeFactors[ n_Integer ] := Flatten[ Table[ # [ [ 1 ] ], {1} ] & /@ FactorInteger[ n ] ]; a[ 1 ] := 1; a[ n_ ] := a[ n ] = a[ n - 1 ]*n/Times @@ PrimeFactors[ n ]; Table[ a[ n ], {n, 1, 40} ] PROG (Sage) q=50 # change q for more terms R=[n/prod([x for x in prime_divisors(n)]) for n in [1..q]] [prod(R[0:i+1]) for i in [0..q-1]] # Tom Edgar, Mar 24 2014 CROSSREFS Cf. A084744. Cf. A003557. [From Peter Luschny, Jun 29 2009] Sequence in context: A100943 A152660 A058787 * A265447 A156538 A249768 Adjacent sequences:  A085053 A085054 A085055 * A085057 A085058 A085059 KEYWORD nonn AUTHOR Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 26 2003 EXTENSIONS More terms from Ray Chandler and Robert G. Wilson v, Jun 27 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 19 22:34 EST 2019. Contains 329323 sequences. (Running on oeis4.)