A325450 Numbers k such that sum of digits (k) and sum of digits (k^2) is 9.

9, 18, 45, 90, 180, 351, 450, 900, 1800, 3510, 4500, 9000, 18000, 35100, 45000, 90000, 180000, 351000, 450000, 900000, 1800000, 3510000, 4500000, 9000000, 18000000

Offset: 1

Author

Vincenzo Librandi, May 10 2019

Keywords

• nonn
• base

Comments

A007953(A058369(n)) begins with 1, 9, 1, 9, 10, 9, 10, 10, 9, 18, ...; the 1's come from A011557, the 9's come from this sequence, the 10's come from A325451.

Examples

			a(3) = 45 because 4+5 = 9, 45^2 = 2025, and 2+0+2+5 = 9.
		

Crossrefs

Cf. A004159, A007953, A325451.

Subsequence of A058369 (k and k^2 have same digit sum).

Programs

Magma

[n: n in [1..2*10^7] | &+Intseq(n^2) eq 9  and &+Intseq(n) eq 9];

Mathematica

Select[Range[2 10^7], Total[IntegerDigits[#]]==9&& Total[IntegerDigits[#^2]]==9&]