A309141 - OEIS

A309141

Nonunitary highly composite numbers: numbers with a record number of nonunitary divisors.

1, 4, 8, 16, 24, 36, 48, 72, 144, 216, 288, 360, 576, 720, 1080, 1440, 2160, 2880, 3600, 4320, 5040, 7200, 7560, 10080, 15120, 20160, 25200, 30240, 45360, 50400, 60480, 75600, 100800, 110880, 151200, 221760, 277200, 302400, 332640, 453600, 498960, 554400, 665280

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OFFSET

1,2

COMMENTS

Numbers k with A048105(k) > A048105(j) for all j < k.

The corresponding values of records are 0, 1, 2, 3, 4, 5, 6, 8, 11, 12, 14, 16, 17, 22, 24, 28, 32, 34, 37, 40, 44, 46, 48, 56, 64, 68, 74, 80, 84, 92, 96, ... (see the link for more values)

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..559

Amiram Eldar, Table of n, a(n), A048105(a(n)) for n = 1..559

MATHEMATICA

f[n_] := DivisorSigma[0, n] - 2^PrimeNu[n]; fm=-1; s={}; Do[f1 = f[n]; If[f1 > fm, fm = f1; AppendTo[s, n]], {n, 1, 10^5}]; s

CROSSREFS

Cf. A048105, A002182 (highly composite), A002110 (unitary), A037992 (infinitary), A293185 (bi-unitary), A318278 (exponential).

Sequence in context: A355392 A290498 A137932 * A329882 A309181 A140466

Adjacent sequences: A309138 A309139 A309140 * A309142 A309143 A309144

KEYWORD

nonn

AUTHOR

Amiram Eldar, Jul 14 2019

STATUS

approved