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 A307502 #8 Aug 20 2025 07:59:39
%S A307502 0,1,6,17,36,64,108,172,240,340,444,612,744,980,1164,1504,1704,2172,
%T A307502 2388,2964,3288,3968,4272,5272,5520,6624,7104,8276,8640,10404,10572,
%U A307502 12480,13032,14988,15300,18204,18048,21004,21636,24616,24648,29036,28452,32768,33552,37488
%N A307502 Self-convolution of the Dedekind psi function (A001615).
%H A307502 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DedekindFunction.html">Dedekind Function</a>
%F A307502 G.f.: (Sum_{k>=1} mu(k)^2*x^k/(1 - x^k)^2)^2.
%F A307502 a(n) = Sum_{k=1..n-1} A001615(k)*A001615(n-k).
%F A307502 Conjecture: Sum_{k=1..n} a(k) ~ 75 * n^4 / (8 * Pi^4). - _Vaclav Kotesovec_, Aug 20 2025
%t A307502 Rest[nmax = 46; CoefficientList[Series[Sum[MoebiusMu[k]^2 x^k/(1 - x^k)^2, {k, 1, nmax}]^2, {x, 0, nmax}], x]]
%t A307502 psi[n_] := psi[n] = Sum[MoebiusMu[n/d]^2 d, {d, Divisors @ n}]; a[n_] := a[n] = Sum[psi[k] psi[n - k], {k, 1, n - 1}]; Table[a[n], {n, 1, 46}]
%Y A307502 Cf. A001615, A008683, A065093, A307309.
%K A307502 nonn
%O A307502 1,3
%A A307502 _Ilya Gutkovskiy_, Apr 11 2019