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A335138
a(n) = 1 + Sum_{k=1..2*n} sign((sign(n+Sum_{j=2..k}-|A309229(n,j)|)+1)).
2
3, 5, 5, 5, 6, 7, 9, 10, 7, 11, 8, 13, 8, 15, 12, 11, 10, 11, 11, 13, 13, 14, 13, 14, 13, 15, 14, 15, 13, 19, 17, 17, 17, 19, 16, 19, 15, 14, 17, 17, 15, 22, 17, 23, 20, 19, 17, 19, 17, 19, 19, 21, 19, 21, 19, 21, 21, 21, 21, 23, 22, 22, 22, 19, 21, 23, 23, 23
OFFSET
1,1
COMMENTS
a(n) appears to be asymptotic to sqrt(8*n). Taken from the comment by Lekraj Beedassy in A003418: "An assertion equivalent to the Riemann hypothesis is:
| Sum_{k>=1} (A309229(n, k)/k - 1/k) - n | < sqrt(n) * log(n)^2."
FORMULA
a(n) = 1 + Sum_{k=1..2*n} sign((sign(n+Sum_{j=2..k}-|A309229(n,j)|)+1)).
MATHEMATICA
nn = 68; f[n_] := n; h[n_] := DivisorSum[n, MoebiusMu[#] # &]; A = Accumulate[Table[Table[h[GCD[n, k]], {k, 1, nn}], {n, 1, nn}]]; B = -Abs[A]; B[[All, 1]] = Table[f[n], {n, 1, nn}]; b = 1 + Total[Sign[1 + Sign[Accumulate[Transpose[B]]]]]
CROSSREFS
Cf. A309229.
Sequence in context: A372561 A338058 A365677 * A343691 A196604 A131506
KEYWORD
nonn
AUTHOR
Mats Granvik, Jun 09 2020
STATUS
approved