A085087 a(1) = 1; for n>1, a(n) = a(n-1)*n if n is prime, a(n) = a(n-1)/n if n is composite dividing a(n-1) else a(n) = a(n-1).

1, 2, 6, 6, 30, 5, 35, 35, 35, 35, 385, 385, 5005, 5005, 5005, 5005, 85085, 85085, 1616615, 1616615, 1616615, 1616615, 37182145, 37182145, 37182145, 37182145, 37182145, 37182145, 1078282205, 1078282205, 33426748355, 33426748355

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..500

Formula

Let k be the number of members of A089581 that are <= n; then a(n) = A034386(n)/A099788(k). - David Wasserman, Jan 25 2005

Mathematica

a = {1}; Do[AppendTo[a, If[PrimeQ[n], a[[-1]]*n, If[Divisible[a[[-1]], n], a[[-1]]/n, a[[-1]]]]], {n, 2, 32}]; a (* Ivan Neretin, May 21 2015 *)

Prog

(PARI) print1(k=1); for(n=2, 99, if(isprime(n), k*=n, if(k%n==0, k/=n)); print1(", "k)) \\ Charles R Greathouse IV, May 21 2015

Crossrefs

Cf. A034386, A089581, A099788.

Sequence in context: A005226 A087310 A130087 * A072983 A379580 A055204

Adjacent sequences: A085084 A085085 A085086 * A085088 A085089 A085090

Keyword

nonn

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jul 02 2003

Extensions

More terms from David Wasserman, Jan 25 2005

Status

approved