%N a(1) = 1; a(n) = smallest multiple of a(n-1) which is a palindromic square.
%C a(5) is greater than 10^23. A naive probabilistic argument suggests that each time the search limit is increased by two orders of magnitude, the chance of finding a(5) is about 1%. The probabilistic argument also suggests that this sequence grows about as fast as the polypowers with base exp(1/2). - _David Wasserman_, Apr 17 2003.
%A _Amarnath Murthy_, Mar 30 2002
%E More terms from _David Wasserman_, Apr 17 2003