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 A290361 #13 Jul 29 2017 04:21:42 %S A290361 0,1,15,111,518,1789,5026,12166,26328,52221,96613,168861,281502, %T A290361 450905,697984,1048972,1536256,2199273,3085467,4251307,5763366, %U A290361 7699461,10149854,13218514,17024440,21703045,27407601,34310745,42606046,52509633,64261884,78129176 %N A290361 Number of 7-leaf rooted trees with n levels. %H A290361 Alois P. Heinz, <a href="/A290361/b290361.txt">Table of n, a(n) for n = 0..1000</a> %H A290361 B. A. Huberman and T. Hogg, <a href="https://doi.org/10.1016/0167-2789(86)90308-1">Complexity and adaptation</a>, Evolution, games and learning (Los Alamos, N.M., 1985). Phys. D 22 (1986), no. 1-3, 376-384. %H A290361 <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a> %H A290361 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1). %F A290361 G.f.: -(4*x^4+21*x^3+27*x^2+8*x+1)*x / (x-1)^7. %F A290361 a(n) = (61*n^6+69*n^5+145*n^4+195*n^3+154*n^2+96*n)/6!. %p A290361 a:= n-> (((((61*n+69)*n+145)*n+195)*n+154)*n+96)*n/6!: %p A290361 seq(a(n), n=0..40); %Y A290361 Row n=7 of A290353. %K A290361 nonn,easy %O A290361 0,3 %A A290361 _Alois P. Heinz_, Jul 28 2017