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A216365 Numbers n such that tau(n)*sigma(n) sets a new record. 1
1, 2, 3, 4, 6, 8, 10, 12, 18, 20, 24, 30, 36, 48, 60, 72, 84, 90, 96, 108, 120, 144, 168, 180, 240, 300, 336, 360, 420, 480, 504, 540, 600, 630, 660, 720, 840, 1008, 1080, 1200, 1260, 1440, 1680, 2100, 2160, 2520, 3360, 3780, 3960, 4200, 4320, 4620, 4680, 5040 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Positions of record values in A064840.

Not identical to A067128; e.g. a(22) = 144 < 168 = A067128(22).

LINKS

Charles R Greathouse IV and Donovan Johnson, Table of n, a(n) for n = 1..400 (first 268 terms from Charles R Greathouse IV)

MATHEMATICA

lst = {}; k = 0; Do[n = DivisorSigma[0, i]*DivisorSigma[1, i]; If[n > k, AppendTo[lst, i]; k = n], {i, 7!}]; lst

PROG

(PARI) r=0; for(n=1, 1e9, t=numdiv(n)*sigma(n); if(t>r, r=t; print1(n", "))) \\ Charles R Greathouse IV, Sep 05 2012

CROSSREFS

Cf. A000005, A000203, A064840.

Sequence in context: A175381 A213623 A074715 * A034287 A067128 A245779

Adjacent sequences:  A216362 A216363 A216364 * A216366 A216367 A216368

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Sep 05 2012

STATUS

approved

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Last modified May 26 13:05 EDT 2019. Contains 323586 sequences. (Running on oeis4.)