A071124 Least of five consecutive numbers which are cubefree and not squarefree, i.e., {k, k+1, k+2, k+3, k+4} are in A067259.

30923, 74849, 96675, 145674, 152339, 204323, 230346, 240425, 255186, 274547, 276650, 338921, 361322, 430073, 432474, 527922, 574674, 671346, 671347, 675491, 697073, 801473, 808155, 826825, 826826, 915857, 939321, 978675, 998522

Offset: 1

Author

Labos Elemer, May 29 2002

Keywords

• nonn

Examples

			30923 = 17*17*107;
30924 = 2*2*3*3*859;
30925 = 5*5*1237;
30926 = 2*7*47*47;
30927 = 3*13*13*61.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A051903, A063528, A067259.

Programs

Mathematica

With[{s = Select[Range[10^6], And[MemberQ[#, 2], FreeQ[#, k_ /; k > 2]] &@ FactorInteger[#][[All, -1]] &]}, Function[t, Part[s, #] &@ SequencePosition[t, {1, 1, 1, 1}][[All, 1]]]@ Differences@ s] (* Michael De Vlieger, Jul 30 2017 *)

Formula

A051903(k) = A051903(k+1) = A051903(k+2) = A051903(k+3) = A051903(k+4) = 2.