A159940 The number of trisubstitution products with composition C_n H_(2n-1) X_2 Y.

4, 16, 46, 106, 208, 364, 586, 886, 1276, 1768, 2374, 3106, 3976, 4996, 6178, 7534, 9076, 10816, 12766, 14938, 17344, 19996, 22906, 26086, 29548, 33304, 37366, 41746, 46456, 51508, 56914, 62686, 68836, 75376, 82318, 89674, 97456, 105676, 114346

Offset

2,1

Comments

See the paper by Valentin Vankov Iliev for details.

Links

Table of n, a(n) for n=2..40.

Valentin Vankov Iliev, A mathematical characterization of the groups of substitution isomerism of the linear alkanes, J. Math. Chem. 47 (2010), 52-61.

Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Formula

a(n) = (2 n^3 - 9 n^2 + 19 n - 14) where n is the number of carbons.

G.f.: 2*x^2*(2+3*x^2+x^3)/(x-1)^4. - R. J. Mathar, Apr 28 2009

Example

The number of trisubstitution products with composition C_n H_(2n-1) X_2 Y for n = 10 is 1276.

Crossrefs

Cf. A002522, A033816, A159938, A159941.

Sequence in context: A097125 A213480 A306302 * A000704 A007315 A055342

Adjacent sequences: A159937 A159938 A159939 * A159941 A159942 A159943

Keyword

nonn,easy

Author

Parthasarathy Nambi, Apr 26 2009

Extensions

More terms from R. J. Mathar, Apr 28 2009

Status

approved