OFFSET
1,1
COMMENTS
Also numbers k such that k concatenated with k+9 gives the product of two numbers which differ by 4. For proof that this is the same sequence compare A116133.
EXAMPLE
61336887//61336891 = 78317867 * 78317873, where // denotes concatenation. 61336887//61336896 = 78317868 * 78317872.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
EXTENSIONS
Edited by N. J. A. Sloane, Apr 11 2007
STATUS
approved