A271895 Expansion of (1-2*x^2) / ( 1-2*x-4*x^2+6*x^3 ).

1, 2, 6, 14, 40, 100, 276, 712, 1928, 5048, 13536, 35696, 95248, 252064, 670944, 1778656, 4728704, 12546368, 33335616, 88484480, 235033216, 623990656, 1657207296, 4400177920, 11685241088, 31027950080, 82395796992, 218791947776, 580999383040, 1542791775232

Offset: 0

Author

R. J. Mathar, Apr 16 2016

Keywords

• nonn
• easy

Comments

Sum of all third elements at level n of the TRIP-Stern sequence corresponding to the permutation triple (e,13,23)

Links

• Ilya Amburg, Krishna Dasaratha, Laure Flapan, Thomas Garrity, Chansoo Lee, Cornelia Mihaila, Nicholas Neumann-Chun, Sarah Peluse, Matthew Stoffregen, Stern Sequences for a Family of Multidimensional Continued Fractions: TRIP-Stern Sequences, arXiv:1509.05239 [math.CO], 2015, Section 7.2.1
• Index entries for linear recurrences with constant coefficients, signature (2,4,-6).

Crossrefs

Cf. A271486 (maximum at level n).

Programs

PARI

x='x+O('x^99); Vec((1-2*x^2)/(1-2*x-4*x^2+6*x^3)) \\ Altug Alkan, Apr 16 2016

Formula

a(n) >= 2^n.