A171666 Numbers n such that n, n+1 and n+2 have the same number of divisors, and that number of divisors is larger than 4.

230, 242, 243, 374, 603, 663, 902, 1105, 1274, 1309, 1334, 1832, 1885, 1924, 2013, 2054, 2133, 2264, 2343, 2504, 2523, 2665, 2696, 2936, 3110, 3655, 3656, 3729, 4203, 4401, 4503, 4504, 4614, 4669, 4695, 4807, 4923, 5133, 5862, 5943, 5944, 6054, 6061

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Dec 14 2009

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005237, A005238, A171665

Programs

Mathematica

f[n_]:=Length[Divisors[n]]; lst={};Do[If[f[n]==f[n+1]==f[n+2]&&f[n]>4,AppendTo[lst,n]],{n,8!}];lst
Flatten[Position[Partition[DivisorSigma[0,Range[7000]],3,1],?(Length[ Union[#]]==1&&#[[1]]>4&),{1},Heads->False]] (* _Harvey P. Dale, Jul 20 2014 *)
SequencePosition[Table[If[DivisorSigma[0,n]>4,DivisorSigma[0,n],n],{n,6100}],{x_,x_,x_}][[All,1]] (* Harvey P. Dale, Nov 15 2021 *)