A271358 a(n) = k*Fibonacci(2*n+1) + (k+1)*Fibonacci(2*n), where k=4.
4, 13, 35, 92, 241, 631, 1652, 4325, 11323, 29644, 77609, 203183, 531940, 1392637, 3645971, 9545276, 24989857, 65424295, 171283028, 448424789, 1173991339, 3073549228, 8046656345, 21066419807, 55152603076, 144391389421, 378021565187, 989673306140
Offset: 0
Links
- Colin Barker, Table of n, a(n) for n = 0..1000
- Boothby, T.; Burkert, J.; Eichwald, M.; Ernst, D. C.; Green, R. M.; Macauley, M. On the cyclically fully commutative elements of Coxeter groups, J. Algebr. Comb. 36, No. 1, 123-148 (2012) Table 1 CFC Type D.
- Index entries for linear recurrences with constant coefficients, signature (3,-1).
Crossrefs
Programs
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Magma
k:=4; [k*Fibonacci(2*n+1)+(k+1)*Fibonacci(2*n): n in [0..30]]; // Bruno Berselli, Apr 06 2016
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PARI
a(n) = 4*fibonacci(2*n+1) + 5*fibonacci(2*n)
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PARI
Vec((4+x)/(1-3*x+x^2) + O(x^50))
Formula
Extensions
Changed offset and adapted definition, programs and formulas by Bruno Berselli, Apr 06 2016