A167885 n-th single or isolated number*n-th non-single or nonisolated number.

0, 4, 18, 60, 126, 184, 270, 370, 462, 611, 742, 900, 1072, 1224, 1501, 1660, 1869, 2134, 2448, 2700, 2938, 3429, 3668, 4002, 4650, 5024, 5379, 5678, 6055, 6480, 7296, 7722, 8440, 9143, 9804, 10252, 10800, 11546, 12336, 12887, 13500, 14127, 14664

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 14 2009, Nov 15 2009

Keywords

• nonn

Examples

			a(1)=2*0=0, a(2)=4*1=4, a(3)=6*3=18, a(4)=12*5=60.
		

Crossrefs

Cf. A167706, A167707.

Formula

a(n)=A167706(n)*A167707(n).

Extensions

All terms > 1900 corrected by R. J. Mathar, May 30 2010