A225429 Number of n-digit numbers x such that the digits of x^2 occur with frequency 2.

0, 1, 8, 38, 165, 1020, 5360, 24553, 98442

Offset: 1

Author

T. D. Noe, Jun 21 2013

Keywords

• nonn
• base

Comments

After a(10), all terms are 0.

Examples

			The only two-digit number is 88, whose square is 7744.
		

Crossrefs

Cf. A225428.

Programs

Mathematica

cnt = 0; t2 = Table[x = Floor[Sqrt[10] * 10^(n-1)]; While[x < 10^n, If[Union[Last[Transpose[Tally[IntegerDigits[x^2]]]]] == {2}, cnt++]; x++]; cnt, {n, 6}]; Join[{0}, Differences[t2]]