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 A055358 #12 Mar 15 2022 04:30:28 %S A055358 6,96,874,6040,35458,187288,920350,4297240,19332662,84615152, %T A055358 362772194,1531122296,6385177274,26382771464,108232980822, %U A055358 441554515704,1793612585550,7261158583200,29318205685050 %N A055358 Number of increasing mobiles (circular rooted trees) with n nodes and 4 leaves. %H A055358 Georg Fischer, <a href="/A055358/b055358.txt">Table of n, a(n) for n = 5..250</a> %H A055358 <a href="/index/Mo#mobiles">Index entries for sequences related to mobiles</a> %F A055358 For n>0, a(n) = 31*2^(2*n - 3)/9 - 5*(n+2)*3^n/12 + (n^2 + 2*n + 2)*2^(n-2) - n^3/6 - n/4 - 1/18. - _Vaclav Kotesovec_, Mar 15 2022 %Y A055358 Column 4 of A055356. %K A055358 nonn %O A055358 5,1 %A A055358 _Christian G. Bower_, May 15 2000