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 A339785 #8 Jan 10 2021 02:13:39 %S A339785 0,1,2,7,24,91,354,1491,6504,29711,139616,674696,3328798,16730955, %T A339785 85382210,441571216,2310003732,12206975528,65082858008,349756996762, %U A339785 1892980028014,10310987833049,56489307860860,311112321625754,1721692801914844,9569930999155801,53410232801675436 %N A339785 Number of homeomorphically irreducible leaf colored trees with n leaves using exactly 2 colors. %H A339785 Andrew Howroyd, <a href="/A339785/b339785.txt">Table of n, a(n) for n = 1..500</a> %F A339785 a(n) = A339782(n) - 2*A007827(n). %o A339785 (PARI) my(N=25); (U(N,2)-2*U(N,1))[2..1+N] \\ See A339780 for U(n,k). %Y A339785 Column k=2 of A339780. %Y A339785 Cf. A007827, A339782. %K A339785 nonn %O A339785 1,3 %A A339785 _Andrew Howroyd_, Dec 16 2020