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 A159941 Number of trisubstituted linear alkanes of composition C_n H_(2n-1) XYZ. 0
 8, 32, 92, 212, 416, 728, 1172, 1772, 2552, 3536, 4748, 6212, 7952, 9992, 12356, 15068, 18152, 21632, 25532, 29876, 34688, 39992, 45812, 52172, 59096, 66608, 74732, 83492, 92912, 103016, 113828, 125372, 137672 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS See the paper by Valentin Vankov Iliev for details. LINKS V. V. Iliev, A mathematical characterization of the groups of substitution isomerism of the linear alkanes, J. Math. Chem. 45 (2009), p 52-61. Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA a(n) = (4*n^3 - 18*n^2 + 38*n - 28) where n is the number of carbons. a(n) = 2*A159940(n). [R. J. Mathar, Jul 08 2009] G.f.: 4*x^2*(2+3*x^2+x^3)/(1-x)^4. [Colin Barker, Aug 07 2012] a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). - Wesley Ivan Hurt, May 28 2021 EXAMPLE The number of trisubstituted linear decane (n = 10) is 2552. CROSSREFS Cf. A002522, A033816. Sequence in context: A014819 A033155 A132117 * A053348 A019256 A286399 Adjacent sequences:  A159938 A159939 A159940 * A159942 A159943 A159944 KEYWORD nonn,easy AUTHOR Parthasarathy Nambi, Apr 26 2009 STATUS approved

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Last modified July 25 23:39 EDT 2021. Contains 346294 sequences. (Running on oeis4.)