This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A325450 #16 Sep 08 2022 08:46:24 %S A325450 9,18,45,90,180,351,450,900,1800,3510,4500,9000,18000,35100,45000, %T A325450 90000,180000,351000,450000,900000,1800000,3510000,4500000,9000000, %U A325450 18000000 %N A325450 Numbers k such that sum of digits (k) and sum of digits (k^2) is 9. %C A325450 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. %e A325450 a(3) = 45 because 4+5 = 9, 45^2 = 2025, and 2+0+2+5 = 9. %t A325450 Select[Range[2 10^7], Total[IntegerDigits[#]]==9&& Total[IntegerDigits[#^2]]==9&] %o A325450 (Magma) [n: n in [1..2*10^7] | &+Intseq(n^2) eq 9 and &+Intseq(n) eq 9]; %Y A325450 Cf. A004159, A007953, A325451. %Y A325450 Subsequence of A058369 (k and k^2 have same digit sum). %K A325450 nonn,base %O A325450 1,1 %A A325450 _Vincenzo Librandi_, May 10 2019