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 A318681 #13 Sep 02 2018 17:07:31
%S A318681 1,2,9,12,25,18,49,40,243,50,121,108,169,98,225,560,289,486,361,300,
%T A318681 441,242,529,360,1875,338,3645,588,841,450,961,2016,1089,578,1225,
%U A318681 2916,1369,722,1521,1000,1681,882,1849,1452,6075,1058,2209,5040,7203,3750,2601,2028,2809,7290,3025,1960,3249,1682,3481,2700
%N A318681 a(n) = n * A299149(n).
%C A318681 Dirichlet convolution of a(n)/A299150(n) with itself gives A000290, the squares, like gives also the self-convolution of A318649(n)/A318512(n), as it is the same ratio reduced to its lowest terms. However, in contrast to A318649, this sequence is multiplicative as both A000027 and A299149 are multiplicative sequences (also, because A000290 and A299150 are both multiplicative).
%C A318681 A007814 gives the 2-adic valuation of this sequence, because there are no even terms in A299149.
%H A318681 Antti Karttunen, <a href="/A318681/b318681.txt">Table of n, a(n) for n = 1..16384</a>
%H A318681 Wikipedia, <a href="https://en.wikipedia.org/wiki/Dirichlet_convolution">Dirichlet convolution</a>
%F A318681 a(n) = n * A299149(n).
%F A318681 a(n)/A299150(n) = A318649(n)/A318512(n).
%o A318681 (PARI)
%o A318681 up_to = 65537;
%o A318681 DirSqrt(v) = {my(n=#v, u=vector(n)); u[1]=1; for(n=2, n, u[n]=(v[n]/v[1] -
%o A318681 sumdiv(n, d, if(d>1&&d<n, u[d]*u[n/d], 0)))/2); u};
%o A318681 v299149_50 = DirSqrt(vector(up_to, n, n));
%o A318681 A299149(n) = numerator(v299149_50[n]);
%o A318681 A318681(n) = (n*A299149(n));
%Y A318681 Cf. A000290, A299149, A299150, A318512, A318649, A318680.
%K A318681 nonn,mult
%O A318681 1,2
%A A318681 _Antti Karttunen_, Sep 02 2018