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A220493
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Fibonacci 15-step numbers, a(n) = a(n-1) + a(n-2) + ... + a(n-15).
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2
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1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32767, 65533, 131064, 262124, 524240, 1048464, 2096896, 4193728, 8387328, 16774400, 33548288, 67095552, 134189056, 268374016, 536739840, 1073463296, 2146893825, 4293722117, 8587313170
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OFFSET
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1,3
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COMMENTS
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Also called Pentadecanacci numbers. In previous similar sequences, a(1), ..., a(n-1) have been set equal to zero and a(n)=1. For example, A168084 (Fibonacci 13-step numbers) has 12 0's as the first 12 terms and a(13)=1.
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LINKS
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Robert Israel, Table of n, a(n) for n = 1..3320
M. Janjic, On Linear Recurrence Equations Arising from Compositions of Positive Integers, J. Int. Seq. 18 (2015) # 15.4.7.
Tony D. Noe and Jonathan Vos Post, Primes in Fibonacci n-step and Lucas n-step Sequences, J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4.
Index entries for linear recurrences with constant coefficients, signature (1,1,1,1,1,1,1,1,1,1,1,1,1,1,1).
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FORMULA
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G.f.: x/(1-Sum_{k=1..15} x^k). - Robert Israel, Feb 19 2019
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MAPLE
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f:= gfun:-rectoproc({a(n) = add(a(n-i), i=1..15), seq(a(n)=0, n=-14..0), a(1)=1}, a(n), remember):
map(f, [$1..100]); # Robert Israel, Feb 19 2019
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MATHEMATICA
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FibonacciSequence[n_, kMax_] := Module[{a, s}, a = Join[{1}, Table[0, {n - 1}]]; lst = {}; Table[s = Plus @@ a; a = RotateLeft[a]; a[[n]] = s, {k, 1, kMax}]]; FibonacciSequence[15, 50] (* T. D. Noe, Feb 20 2013 *)
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CROSSREFS
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Cf. A000045 (Fibonacci), A000073 (tribonacci), A000078 (tetranacci), A001591 (pentanacci).
Sequence in context: A220469 A328679 A220051 * A320487 A323830 A118655
Adjacent sequences: A220490 A220491 A220492 * A220494 A220495 A220496
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KEYWORD
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nonn,easy
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AUTHOR
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Ruskin Harding, Feb 20 2013
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STATUS
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approved
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