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A278570
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a(n) = maximum absolute value of coefficients in the cyclotomic polynomial C(N,x), where N = n-th number which a product of three distinct odd primes = A046389(n).
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2
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2, 2, 2, 1, 2, 2, 2, 2, 2, 3, 1, 2, 1, 2, 1, 1, 2, 2, 3, 2, 2, 2, 2, 1, 1, 3, 2, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 1, 2, 3, 2, 2, 2, 1, 2, 3, 1, 1, 1, 2, 2, 2, 1, 2, 3, 1, 2, 3, 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 3, 1, 2, 2, 2, 1, 3, 2
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OFFSET
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1,1
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REFERENCES
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Don Reble, Posting to Sequence Fans Mailing List, Nov 26 2016
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LINKS
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MAPLE
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with(numtheory):
b:= proc(n) option remember; local k;
for k from 2+`if`(n=1, 1, b(n-1)) by 2 while
bigomega(k)<>3 or nops(factorset(k))<>3 do od; k
end:
a:= n-> max(map(abs, [coeffs(cyclotomic(b(n), x))])):
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MATHEMATICA
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b[n_] := b[n] = (For[k = 2 + If[n == 1, 1, b[n-1]], PrimeOmega[k] != 3 || PrimeNu[k] != 3, k += 2]; k);
a[n_] := Max @ Abs @ CoefficientList[Cyclotomic[b[n], x], x];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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