login
A335130
a(n) = 1 + Sum_{k=1..n} sign((sign(n+Sum_{j=2..k}-|A334312(n,j)|)+1)).
1
2, 3, 4, 5, 6, 5, 7, 7, 10, 7, 11, 10, 11, 10, 11, 11, 14, 13, 14, 13, 13, 11, 15, 12, 17, 13, 17, 13, 19, 13, 14, 15, 15, 15, 17, 17, 17, 19, 19, 17, 19, 17, 18, 17, 17, 18, 21, 19, 22, 21, 21, 19, 21, 21, 23, 23, 19, 19, 26, 19, 19, 23, 23, 23, 29, 21, 22, 21, 23, 21, 23, 22, 23, 23, 28, 23, 31, 23, 26, 25
OFFSET
1,1
COMMENTS
a(n) appears to be asymptotic to sqrt(8*n).
FORMULA
a(n) = 1 + Sum_{k=1..n} sign((sign(n+Sum_{j=2..k}-|A334312(n,j)|)+1)).
MATHEMATICA
nn = 80; varphi[n_] := DivisorSum[n, MoebiusMu[#] # &]; A = Table[Table[Sum[If[n >= k, varphi[GCD[i, k]], 0], {i, k, n}], {k, 1, nn}], {n, 1, nn}]; vv = Table[1 + Sum[Sign[(1 + Sign[Sum[If[j == 1, A[[n, j]], -Abs[A[[n, j]]]], {j, 1, k}]])], {k, 1, n}], {n, 1, nn}]
CROSSREFS
Cf. A334312.
Sequence in context: A187786 A002330 A374211 * A373595 A358747 A373251
KEYWORD
nonn
AUTHOR
Mats Granvik, May 24 2020
STATUS
approved