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A329004
a(n) is the largest index in [n] that maximizes tau.
2
1, 2, 3, 4, 4, 6, 6, 8, 8, 10, 10, 12, 12, 12, 12, 12, 12, 18, 18, 20, 20, 20, 20, 24, 24, 24, 24, 24, 24, 30, 30, 30, 30, 30, 30, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 72
OFFSET
1,2
LINKS
FORMULA
a(n) = n <=> n in { A067128 }. - Alois P. Heinz, Jun 11 2020
MAPLE
a:= proc(n) option remember; uses numtheory; `if`(n=1, 1,
(t-> `if`(tau(n)<tau(t), t, n))(a(n-1)))
end:
seq(a(n), n=1..100); # Alois P. Heinz, Jun 11 2020
MATHEMATICA
dmax = 0; nmax = 1; seq = {}; Do[If[(d = DivisorSigma[0, n]) >= dmax, dmax = d; nmax = n]; AppendTo[seq, nmax], {n, 1, 72}]; seq (* Amiram Eldar, Jun 11 2020 *)
PROG
(Haskell) a329004 = map fst $ scanl1 (\x y -> maximumBy (comparing snd) [x, y]) $ zip [1..] a000005
CROSSREFS
Sequence in context: A111939 A253248 A341112 * A003962 A102443 A102441
KEYWORD
nonn
AUTHOR
Peter Andrew, Jun 10 2020
STATUS
approved