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Numbers whose square has initial digit '3'.
2

%I #18 Aug 09 2021 02:34:17

%S 6,18,19,55,56,57,58,59,60,61,62,63,174,175,176,177,178,179,180,181,

%T 182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,

%U 199,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563

%N Numbers whose square has initial digit '3'.

%H Seiichi Manyama, <a href="/A045857/b045857.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[600],IntegerDigits[#^2][[1]]==3&] (* _Harvey P. Dale_, Jan 09 2020 *)

%o (PARI) isok(n) = digits(n^2)[1] == 3; \\ _Michel Marcus_, May 28 2017

%Y Cf. A045786.

%K nonn,base

%O 1,1

%A _Jeff Burch_