OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..2000
EXAMPLE
80919 * (80919 + 1) = 6547965480, the concatenation of 65479 and 65479 + 1.
MATHEMATICA
Union @@ ((x /. List@ ToRules@ Reduce[x (x+1) == 10^# y +y+1 && x>0 && 10^(#-1) <= y+1 < 10^#, {x, y}, Integers]) & /@ Range[13] /. x->{}) (* Giovanni Resta, Jul 08 2018 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
EXTENSIONS
More terms from Giovanni Resta, Jul 08 2018
STATUS
approved