A136831 Numbers k such that k and k^2 use only the digits 0, 1, 2 and 7.

0, 1, 10, 11, 100, 101, 110, 1000, 1001, 1010, 1011, 1100, 1101, 10000, 10001, 10010, 10011, 10100, 10110, 11000, 11001, 11010, 100000, 100001, 100010, 100011, 100100, 100101, 100110, 101000, 101001, 101100, 110000, 110001, 110010, 110100, 1000000, 1000001, 1000010, 1000011, 1000100, 1000101, 1000110, 1001000, 1001010, 1001100, 1010000

Offset: 1

Author

Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008

Keywords

• base
• nonn

Comments

Generated with DrScheme.

Examples

			110100010001011^2 = 12122012202222722220221022121.
		

Links

• Jonathan Wellons, Table of n, a(n) for n = 1..1361
• J. Wellons, Tables of Shared Digits [archived]

Programs

Mathematica

With[{c={0,1,2,7}},Select[FromDigits/@Tuples[c,7],SubsetQ[ c,IntegerDigits[ #^2]]&]] (* Harvey P. Dale, Dec 21 2014 *)