A161672 Half the product of all numbers from A141468(n) up to prime(n).

0, 3, 10, 21, 3960, 77220, 490089600, 1523733120, 2075793350400, 50710801232931840000, 3144069676441774080000, 19348101737674447004467200000, 137500509682406403378413568000000

Offset

1,2

Links

Michael De Vlieger, Table of n, a(n) for n = 1..99

Formula

a(n) = prime(n)!/ (2*(A141468(n)-1)!).

Example

a(1)=0 is the product 0*1*2/2. a(2) is the product 1*2*3/2 = 3. a(3)=10 is the product 4*5/2.

Mathematica

f[n_] := FixedPoint[n + PrimePi@ # &, n + PrimePi@ n]; Array[1/2*Times @@ Range[f[# - 1], Prime[#]] &, 13] (* Michael De Vlieger, Mar 22 2022, after Robert G. Wilson v at A141468 *)

Crossrefs

Cf. A000040, A141468.

Sequence in context: A158030 A068082 A058077 * A190092 A174459 A326124

Adjacent sequences: A161669 A161670 A161671 * A161673 A161674 A161675

Keyword

nonn

Author

Juri-Stepan Gerasimov, Jun 16 2009

Extensions

a(0) replaced by 0 - R. J. Mathar, May 21 2010

Status

approved