A329004 a(n) is the largest index in [n] that maximizes tau.

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

Author

Peter Andrew, Jun 10 2020

Keywords

• nonn

Links

• Peter Andrew, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A000005, A067128.

Programs

Haskell

a329004 = map fst $ scanl1 (\x y -> maximumBy (comparing snd) [x,y]) $ zip [1..] a000005

Maple

a:= proc(n) option remember; uses numtheory; `if`(n=1, 1,
      (t-> `if`(tau(n)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 *)

Formula

a(n) = n <=> n in { A067128 }. - Alois P. Heinz, Jun 11 2020