A181643 a(n) is the smallest value such that a(n)*[a(n)+n]*[a(n)+n+n]=y^2 is a perfect square.

0, 0, 0, 0, 40, 6, 18, 0, 0, 0, 0, 0, 0, 4, 10, 0, 0, 0, 0, 5, 7, 0, 0, 1, 0, 0, 0, 72, 0, 15, 0, 0, 0, 128, 0, 0, 0, 0, 936, 0, 800, 0, 0, 0, 360, 196, 0, 0, 0, 0, 0, 0, 0, 54

Offset: 1

Author

Carmine Suriano, Nov 03 2010, corrected Nov 10 2010

Keywords

• nonn

Comments

For a given n there is more than one solution.

Examples

			a(5)=40 since 40*(40+5)*(40+5+5)=40*45*50=90000=300^2
		

Crossrefs

Cf. A115878, A181646.