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

Author

Parthasarathy Nambi, Apr 26 2009

Keywords

• nonn
• easy

Comments

See the paper by Valentin Vankov Iliev for details.

Examples

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

Links

• 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).

Crossrefs

Cf. A002522, A033816, A159938, A159941.

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

Extensions

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