A331999 a(n) is the product of n, the n-th prime and the n-th composite number.

8, 36, 120, 252, 550, 936, 1666, 2280, 3312, 5220, 6820, 9324, 11726, 14448, 17625, 22048, 27081, 30744, 38190, 45440, 50589, 59092, 66815, 76896, 92150, 102414, 111240

Offset: 1

Author

Soham B. Patel, Feb 04 2020

Keywords

• nonn

Examples

			For n=1; prime(1)=2, composite(1)=4; a(1) = 8;
For n=2; prime(2)=3, composite(2)=6; a(2) = 36;
For n=3; prime(3)=5, composite(3)=8; a(3) = 120.
		

Crossrefs

Cf. A000040, A002808, A067563.

Programs

Mathematica

m = 105; p = Select[Range[m], PrimeQ]; n = Length[p]; c = Complement[Range[2, m], p][[1;;n]]; p * c * Range[n] (* Amiram Eldar, Feb 12 2020 *)

Formula

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

a(n) = n*A067563(n).