A216365 Numbers n such that tau(n)*sigma(n) sets a new record.

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

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 A369519 A213623 * A034287 A067128 A245779

Adjacent sequences: A216362 A216363 A216364 * A216366 A216367 A216368

Keyword

nonn

Author

Arkadiusz Wesolowski, Sep 05 2012

Status

approved