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

0, 1, 2, 3, 7, 10, 12, 20, 21, 30, 38, 70, 97, 100, 102, 107, 120, 138, 200, 201, 210, 212, 300, 380, 648, 700, 701, 951, 970, 997, 1000, 1002, 1007, 1020, 1049, 1070, 1200, 1380, 1393, 2000, 2001, 2010, 2100, 2120, 3000, 3148, 3153, 3451, 3743, 3747, 3800, 4462

Offset: 1

Author

Colin Barker, Apr 21 2017

Keywords

• nonn
• base

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 350 terms from Colin Barker)

Crossrefs

Cf. A000290, A019544, A046030.

Programs

Mathematica

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

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)

Formula

a(n) = sqrt(A019544(n)). - Alois P. Heinz, Apr 21 2017