OFFSET
0,5
COMMENTS
Conjectures: { Fib(n) | n in naturals } = { a(n) | n in naturals, a(n) >= 0 } = { a(n) | n in naturals, n not of the form 6*n+2 } (naturals include 0).
Floretion Algebra Multiplication Program, FAMP Code: 4teszapseq[(- .5'j + .5'k - .5j' + .5k' - 'ii' - .5'ij' - .5'ik' - .5'ji' - .5'ki')*( + .5'j + .5i' + .5'ik' + .5'jk' + .5'ki' + .5'kj')]
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,4,0,0,0,0,0,1).
FORMULA
a(6*n+2) = - A048876(n) (Generalized Pellian with second term of 7), conjecture.
From Colin Barker, May 11 2019: (Start)
G.f.: (1 - x)*(1 + x)^2*(1 + x^2)*(1 - x^2 + 2*x^3 + x^4) / ((1 - x^2 - x^4)*(1 + x^2 + 2*x^4 - x^6 + x^8)).
a(n) = 4*a(n-6) + a(n-12) for n>11. (End)
MATHEMATICA
CoefficientList[Series[(1-x)(1+x)^2(1+x^2)(1-x^2+2x^3+x^4)/((1-x^2-x^4)(1+x^2+2x^4-x^6+x^8)), {x, 0, 80}], x] (* or *) LinearRecurrence[{0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 1}, {1, 1, -1, 1, 2, 0, 5, 3, -7, 3, 8, 0}, 80] (* Harvey P. Dale, Jun 10 2024 *)
PROG
(PARI) Vec((1 - x)*(1 + x)^2*(1 + x^2)*(1 - x^2 + 2*x^3 + x^4) / ((1 - x^2 - x^4)*(1 + x^2 + 2*x^4 - x^6 + x^8)) + O(x^55)) \\ Colin Barker, May 11 2019
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Creighton Dement, May 24 2005
STATUS
approved