A116133 Numbers k such that k concatenated with k-4 gives the product of two numbers which differ by 9.

64, 1876, 3214, 8776, 17227120144584448354, 19391087990479091186, 21557280540171744040, 23970390649400564404, 26051259424903756364, 28697643366269876506, 31320461807899711990, 34215988012600009664

Offset: 1

Author

Giovanni Resta, Feb 06 2006

Keywords

• nonn
• base

Comments

Also numbers k such that k concatenated with k+4 gives the product of two numbers which differ by 7.

Since k*(10^j+1) + 4 = m*(m+7) iff k*(10^j+1) - 4 = m*(m+7) - 8 = (m-1)*(m+8) = M*(M+9) this is trivially the same sequence. - N. J. A. Sloane, Apr 11 2007

Examples

			8776//8772 = 9364 * 9373, where // denotes concatenation. Also 8776//8780 = 9365 * 9372.
		

Crossrefs

Cf. A116132, A116140, A116264.

Cf. A116180, A116187, A116189, A116195, A116319.

Extensions

Edited by N. J. A. Sloane, Apr 11 2007