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A261713 Natural numbers that can be split into two squares, leading zeros allowed.

%I A261713 #32 Aug 30 2015 11:43:51
%S A261713 10,11,14,19,40,41,44,49,90,91,94,99,100,101,104,109,116,125,136,149,
%T A261713 160,161,164,169,181,250,251,254,259,360,361,364,369,400,401,404,409,
%U A261713 416,425,436,449,464,481,490,491,494,499,640,641,644,649,810,811,814
%N A261713 Natural numbers that can be split into two squares, leading zeros allowed.
%H A261713 Alois P. Heinz, <a href="/A261713/b261713.txt">Table of n, a(n) for n = 1..10000</a>
%p A261713 a:= proc(n) option remember; local d, i, k;
%p A261713       for k from 1+`if`(n=1, 1, a(n-1))
%p A261713       do for i to length(k)-1 do
%p A261713            if issqr(iquo(k, 10^i, 'd')) and
%p A261713               issqr(d) then return k fi
%p A261713          od
%p A261713       od
%p A261713     end:
%p A261713 seq(a(n), n=1..60);  # _Alois P. Heinz_, Aug 29 2015
%t A261713 qQ[n_] := Floor[ Sqrt@ n]^2 == n; ok[n_] := Catch[ Do[ If[ qQ@ Floor[n / 10^k] && qQ@ Mod[n, 10^k],Throw@ True], {k, IntegerLength[n] -1}]; False]; Select[Range@ 1000, ok] (* _Giovanni Resta_, Aug 29 2015 *)
%Y A261713 Cf. A046030, A053061, A168042, A191933.
%K A261713 nonn,base,easy
%O A261713 1,1
%A A261713 _Giovanni Teofilatto_, Aug 29 2015
%E A261713 Name clarified by _Zak Seidov_, Aug 29 2015