Tribonacci related sequences.

[Alec Mihailovs]

----- Original Message ----- 
From: "Creighton Dement" <crowdog at crowdog.de>
> 
> The sequence 1lesforcycrokseq: 1, -2, 5, -11, 26, -53, 104, -198, 375, 
> caught my eye (see http://www.crowdog.de/UnknownTrib.html 
>
> Is it possible for someone to find the g.f. for the first case, above?

In Maple, 

L:=[1, -2, 5, -11, 26, -53, 104, -198, 375, -700, 1299, -2401, 4432,
-8167, 15038, -27676, 50925, -93686, 172337, -316999, 583078,
-1072473, 1972612, -3628226, 6673379, -12274288, 22575967, -41523709,
76374044, -140473803, 258371642]:

gfun[guessgf](L,x);

                      2      6    3      4      5
                 1 + x  + 2 x  - x  + 4 x  - 3 x
              [- --------------------------------, ogf]
                                   8      5
                       -1 - 2 x + x  + 2 x

Alec Mihailovs 
http://math.tntech.edu/alec/