A202170 - OEIS

A202170

Numbers n such that n^2 has only digits 0, 4 and 8.

0, 2, 20, 22, 200, 202, 220, 298, 2000, 2002, 2020, 2022, 2200, 2202, 2980, 20000, 20002, 20020, 20022, 20200, 20220, 22000, 22002, 22020, 28998, 29800, 200000, 200002, 200020, 200022, 200200, 200202, 200220, 202000, 202002, 202200, 220000, 220002, 220020, 220200, 289980, 298000, 632522, 2000000

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OFFSET

1,2

COMMENTS

n = 2*m where m^2 has only digits 0, 1 and 2. - Robert Israel, Jul 17 2018

LINKS

Robert Israel, Table of n, a(n) for n = 1..204

MAPLE

Res:= NULL:

for x from 0 to 3^12 do

L:= convert(x, base, 3);

y:= add(L[i]*10^(i-1), i=1..nops(L));

if issqr(y) then

Res:= Res, 2*sqrt(y)

od:

Res; # Robert Israel, Jul 17 2018

MATHEMATICA

Select[Sqrt[FromDigits[#]]&/@Tuples[{0, 4, 8}, 13], IntegerQ] (* Harvey P. Dale, Sep 08 2024 *)

PROG

(PARI) is_A202170(n)=!setminus(Set(Vec(Str(n^2))), Vec("048"))

(Magma) [ n: n in [0..10^6 by 2] | Set(Intseq(n^2)) subset [0, 4, 8] ]; // Bruno Berselli, Dec 19 2011

CROSSREFS

Cf. A030097, A058441.

Includes 2*A136808.

Sequence in context: A359611 A136909 A169965 * A136908 A196748 A144674

Adjacent sequences: A202167 A202168 A202169 * A202171 A202172 A202173

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Dec 13 2011

EXTENSIONS

More terms from Robert Israel, Jul 17 2018

STATUS

approved