A067563 Product of n-th prime number and n-th composite number.

8, 18, 40, 63, 110, 156, 238, 285, 368, 522, 620, 777, 902, 1032, 1175, 1378, 1593, 1708, 2010, 2272, 2409, 2686, 2905, 3204, 3686, 3939, 4120, 4494, 4796, 5085, 5842, 6288, 6713, 6950, 7599, 7852, 8478, 8965, 9352, 9861, 10382, 10860, 11842, 12159

Offset: 1

Author

Rick L. Shepherd, Jan 29 2002

Keywords

• easy
• nonn

Examples

			E.g. a(4)=63 because the fourth prime is 7 and the fourth composite is 9.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A002808, A064799.

Cf. A127118, A038529.

Programs

Haskell

a067563 n = a000040 n * a002808 n  -- Reinhard Zumkeller, Apr 30 2014

Mathematica

Module[{nn=50,prs,comps,len},prs=Prime[Range[nn]];comps=Complement[ Range[ 4,3nn],prs];len=Min[nn,Length[comps]];Times@@@Thread[ {Take[ prs,len], Take[comps,len]}]](* Harvey P. Dale, Sep 02 2015 *)

Python

from sympy import prime, composite
def A067563(n):
    return prime(n)*composite(n) # Chai Wah Wu, Dec 27 2018

Formula

a(n) = prime(n) * composite(n).