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Numbers whose squares remain squares when prepended with 3 and appended with 25 in base 10.
7

%I #11 Nov 23 2014 03:44:26

%S 84,300,534,392166,25187182950,1675378405584,6748194721416,

%T 212785600968020747190,246624720867076739070,287933960432096347620,

%U 575531271763737072600,1788090425875335255534,89384713972121461210716,14369004287087858450382160956449766

%N Numbers whose squares remain squares when prepended with 3 and appended with 25 in base 10.

%C Conjecture: squares of numbers in the sequence ends in either 00 or 56.

%C a(17) >= 10^50. - _Hiroaki Yamanouchi_, Nov 22 2014

%H Hiroaki Yamanouchi, <a href="/A249969/b249969.txt">Table of n, a(n) for n = 1..16</a>

%e 300^2 = 90000, 39000025 = 6245^2.

%Y Cf. A249968, A249633, A249621.

%K nonn,base

%O 1,1

%A _Chai Wah Wu_, Nov 10 2014