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A186272
The sum of the Fibonacci and shifted tribonacci sequences.
0
1, 1, 2, 3, 4, 8, 13, 22, 38, 65, 112, 194, 337, 588, 1030, 1811, 3196, 5660, 10057, 17926, 32046, 57445, 103236, 185962, 335697, 607184, 1100186, 1996699, 3629044, 6604536, 12033861, 21949630, 40073798, 73225249, 133902408, 245023146, 448626225, 821848892, 1506270798
OFFSET
1,3
COMMENTS
Limit ratio is 1.839286755214161 ...
Last digit sequence has a period of 1860, starting from 3rd element.
FORMULA
a(n) = A000045(n-1) + A000213(n-3).
G.f.: x+x^2 -x^3*(1+x)*(x^2+3*x-2) / ( (x^2+x-1)*(x^3+x^2+x-1) ). - R. J. Mathar, Feb 16 2011
EXAMPLE
a(10) = 65 = Fib(9) + Trib(7) = 34 + 31.
MATHEMATICA
Rest[CoefficientList[Series[x+x^2-x^3(1+x)(x^2+3*x-2)/((x^2+x-1)(x^3+x^2+x-1)), {x, 0, 50}], x]] (* Harvey P. Dale, Feb 24 2011 *)
CROSSREFS
Sequence in context: A219968 A126042 A076227 * A376754 A361722 A092075
KEYWORD
nonn
AUTHOR
Carmine Suriano, Feb 16 2011
STATUS
approved