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 A159940 #6 Dec 01 2021 12:38:28 %S A159940 4,16,46,106,208,364,586,886,1276,1768,2374,3106,3976,4996,6178,7534, %T A159940 9076,10816,12766,14938,17344,19996,22906,26086,29548,33304,37366, %U A159940 41746,46456,51508,56914,62686,68836,75376,82318,89674,97456,105676,114346 %N A159940 The number of trisubstitution products with composition C_n H_(2n-1) X_2 Y. %C A159940 See the paper by Valentin Vankov Iliev for details. %H A159940 Valentin Vankov Iliev, <a href="https://doi.org/10.1007/s10910-009-9534-4">A mathematical characterization of the groups of substitution isomerism of the linear alkanes</a>, J. Math. Chem. 47 (2010), 52-61. %H A159940 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1). %F A159940 a(n) = (2 n^3 - 9 n^2 + 19 n - 14) where n is the number of carbons. %F A159940 G.f.: 2*x^2*(2+3*x^2+x^3)/(x-1)^4. - _R. J. Mathar_, Apr 28 2009 %e A159940 The number of trisubstitution products with composition C_n H_(2n-1) X_2 Y for n = 10 is 1276. %Y A159940 Cf. A002522, A033816, A159938, A159941. %K A159940 nonn,easy %O A159940 2,1 %A A159940 _Parthasarathy Nambi_, Apr 26 2009 %E A159940 More terms from _R. J. Mathar_, Apr 28 2009