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A281488
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a(n) = -Sum_{d divides (n-2), 1 <= d < n} a(d).
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3
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1, -1, -1, 0, 0, 0, -1, 1, 0, -1, 0, 1, -1, 0, 0, 1, 0, -2, -1, 3, 0, -2, 1, 2, -2, -3, 1, 4, -1, -3, 0, 5, -1, -7, 1, 7, -1, -5, 0, 6, 1, -9, -2, 11, 1, -9, -1, 8, 0, -12, 0, 15, 0, -11, -1, 13, 0, -17, 1, 18, -2, -17, 1, 17, 0, -24, 0, 28, -1, -21, 0, 22
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OFFSET
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1,18
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COMMENTS
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a(1) = 1, any other choice simply adds a factor to all terms.
The even bisection of the sequence seems to behave similarly to A281487 with similar asymptotics for |a(n)|. However, the odd bisection shows oscillations with increasing intervals between crossing the zero and increasing amplitude.
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LINKS
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FORMULA
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a(1) = 1,
a(n) = -Sum_{d|(n-2), 1 <= d < n} a(d) for n>1.
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PROG
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a = [1]
for n in range(2, 100):
a.append(-sum(a[d-1] for d in range(1, n) if (n-2)%d == 0))
print(a)
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CROSSREFS
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Cf. A007439 (same formula with overall + instead of -), A281487 (same formula with (n-1) instead of (n-2)), A000123.
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KEYWORD
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AUTHOR
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STATUS
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approved
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