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

Author

Arkadiusz Wesolowski, Sep 05 2012

Keywords

• nonn

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)

Crossrefs

Cf. A000005, A000203, A064840.

Programs

Mathematica

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

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