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%I #18 Apr 22 2023 14:05:11
%S 1,4,9,10,19,24,31,40,51,64,79,90
%N Squares written in base 16. (Next term contains a non-decimal character.)
%C From _Michael De Vlieger_, Nov 12 2014: (Start)
%C The next term contains a nondecimal digit: see the link below for an expanded table of squares with the nondecimal digits.
%C Perfect squares in base 16 must end in one of {0, 1, 4, 9}, similar to perfect squares in base 12.
%C As n increases, a(n) cycles through the end digits thus: {0, 1, 4, 9, 0, 9, 4, 1}.
%C (End)
%D GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See pages 108 and 300.
%e a(8) = 8 * 8 = decimal 64 = 4 * 16 + 0 = "40".
%e a(15) = 15 * 15 = decimal 225 = 14 * 16 + 1. Using the digit "e" to represent digit-14, a(15) = "e1".
%t a004631[n_Integer] := BaseForm[n^2, 16]; a004631/@Range[1024] (* _Michael De Vlieger_, Nov 12 2014 *)
%Y Cf. A000290.
%K base,easy,nonn
%O 0,2
%A _N. J. A. Sloane_
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