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A338399
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Inverse boustrophedon transform of the Fibonacci numbers.
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1
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0, 1, -1, 2, -7, 15, -78, 293, -1629, 8992, -58105, 404669, -3097456, 25617669, -228373197, 2180640110, -22212371403, 240392198791, -2754699284494, 33320193986081, -424246016043385, 5671750867032228, -79436475109286061, 1163129092965592997
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internal format)
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n,k) * A000111(n-k) * A000045(k).
E.g.f.: -(2/sqrt(5)) * exp(x/2) * sinh((sqrt(5)/2)*x) * cos(x) / (1-sin(x)).
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PROG
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(Python)
import sympy
T=[]
for k in range(n+1):
T.append(sympy.fibonacci(k))
T.reverse()
for i in range(k):
T[i+1]=T[i]-T[i+1]
return T[-1]
(Python)
from itertools import accumulate, islice
from operator import sub
def A338399_gen(): # generator of terms
blist, a, b = tuple(), 0, 1
while True:
yield (blist := tuple(accumulate(reversed(blist), func=sub, initial=a)))[-1]
a, b = b, a+b
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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