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A285550 Numbers k such that the digits of k^2 are squares. 5

%I #21 Jun 14 2022 16:41:20

%S 0,1,2,3,7,10,12,20,21,30,38,70,97,100,102,107,120,138,200,201,210,

%T 212,300,380,648,700,701,951,970,997,1000,1002,1007,1020,1049,1070,

%U 1200,1380,1393,2000,2001,2010,2100,2120,3000,3148,3153,3451,3743,3747,3800

%N Numbers k such that the digits of k^2 are squares.

%H Giovanni Resta, <a href="/A285550/b285550.txt">Table of n, a(n) for n = 1..10000</a> (first 350 terms from Colin Barker)

%F a(n) = sqrt(A019544(n)). - _Alois P. Heinz_, Apr 21 2017

%t Sqrt[#]&/@Select[Range[0,3800]^2,SubsetQ[{0,1,4,9},IntegerDigits[#]]&] (* _Harvey P. Dale_, Jun 14 2022 *)

%o (PARI) maxk=10000; L=List(); for(k=0, maxk, if(setminus(vecsort(digits(k^2),,8), [0,1,4,9]) == [], listput(L, k))); Vec(L)

%Y Cf. A000290, A019544, A046030.

%K nonn,base

%O 1,3

%A _Colin Barker_, Apr 21 2017

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Last modified June 8 02:08 EDT 2024. Contains 373206 sequences. (Running on oeis4.)