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 A055341 #18 Feb 14 2025 10:21:18 %S A055341 1,3,8,19,37,66,110,172,257,371,518,705,939,1226,1574,1992,2487,3069, %T A055341 3748,4533,5435,6466,7636,8958,10445,12109,13964,16025,18305,20820, %U A055341 23586,26618,29933,33549,37482,41751,46375,51372,56762,62566,68803 %N A055341 Number of mobiles (circular rooted trees) with n nodes and 3 leaves. %H A055341 <a href="/index/Mo#mobiles">Index entries for sequences related to mobiles</a> %H A055341 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2,-1,0,1,2,-3,1). %F A055341 G.f.: x^4(-x^4+2x^3+x^2+1)/((1-x^2)(1-x^3)(1-x)^3). %p A055341 A055341 := proc(n) %p A055341 n^2/12+n/2-215/288+n^4/48-n^3/9-(-1)^n/32-2*A049347(n)/9 ; %p A055341 end proc: %p A055341 seq(A055341(n),n=4..40 ) ; # reuses code of A049347 _R. J. Mathar_, Feb 14 2025 %Y A055341 Column 3 of A055340. %K A055341 nonn %O A055341 4,2 %A A055341 _Christian G. Bower_, May 14 2000