

A329004


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


1



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
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OFFSET

1,2


LINKS

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


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(n1)))
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

Cf. A000005, A067128.
Sequence in context: A111939 A253248 A341112 * A003962 A102443 A102441
Adjacent sequences: A329001 A329002 A329003 * A329005 A329006 A329007


KEYWORD

nonn


AUTHOR

Peter Andrew, Jun 10 2020


STATUS

approved



