A247263 - OEIS

%I #10 Sep 14 2014 00:22:08

%S 375,2371875,

%T 6816208478590683385931482169914619837072677910327911376953125,

%U 140221743281593822163509288486586064542459780568606220185756683349609375,818488127823449514709977488133381451695186814276894438080489635467529296875

%N Positive numbers not divisible by 10 whose squares remain squares when prefixed with 1000.

%H Chai Wah Wu, <a href="/A247263/b247263.txt">Table of n, a(n) for n = 1..53</a>

%e 375^2 = 140625 and 1000140625 is square.

%o (PARI)

%o for(n=1,10^20,if(n^2%100&&issquare(10^(#Str(n^2)+3)+n^2),print1(n^2,", "))) \\ _Derek Orr_, Sep 13 2014

%Y Cf. A242268, A247261, A247262, A247264.

%K nonn,base

%O 1,1

%A _Chai Wah Wu_, Sep 11 2014