cp's OEIS Frontend

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.

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A260220 Number of symmetry-allowed, linearly-independent terms at n-th order in the expansion of T1 x t1 rovibrational perturbation matrix H(Jx,Jy,Jz).

Original entry on oeis.org

1, 1, 3, 2, 6, 4, 10, 6, 15, 9, 21, 12, 28, 16, 36, 20, 45, 25, 55, 30, 66, 36, 78, 42, 91, 49, 105, 56, 120, 64, 136, 72, 153, 81, 171, 90, 190, 100, 210, 110, 231, 121, 253, 132, 276, 144, 300, 156, 325, 169, 351, 182, 378, 196, 406, 210, 435, 225, 465, 240
Offset: 0

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Author

Bradley Klee, Jul 19 2015

Keywords

Comments

a(n) are also coefficients in a Molien Series for G = H x T x O, where H is Hermitian conjugacy, T is Time-reversal, and O is Octahedral. |G| = 96.
Harter et al. give some terms. Compare first four values of a(n) with Eq. 8 of Dhont, Sadovskií, Zhilinskií, and Boudon (see links).

Crossrefs

Programs

  • Mathematica
    (D[(1 + x + x^2)/((1 - x^2)^3 (1 + x^2)), {x, #}]/#! /. x -> 0) & /@
    Range[0, 20]
    CoefficientList[Series[(1 + x + x^2)/((1 - x^2)^3 (1 + x^2)), {x, 0, 70}], x] (* Vincenzo Librandi, Jul 22 2015 *)
    LinearRecurrence[{0, 2, 0, 0, 0, -2, 0, 1}, {1, 1, 3, 2, 6, 4, 10, 6}, 60] (* Robert G. Wilson v, Jul 22 2015 *)
  • PARI
    Vec((1 + x + x^2)/((1 - x^2)^3*(1 + x^2)) + O(x^80)) \\ Michel Marcus, Jul 20 2015

Formula

G.f.: (1 + x + x^2)/((1 - x^2)^3*(1 + x^2)).
a( 4 n+1 ) = A000290(n+1);
a( 4 n+3 ) = 2*A000217(n+1);
a( 2 n ) = A000217(n+1).

Extensions

More terms from Michel Marcus, Jul 20 2015
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