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

1,1

Links

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

Formula

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

Example

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

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 *)

Crossrefs

Cf. A051903, A063528, A067259.

Sequence in context: A236899 A258891 A237469 * A250590 A338948 A186918

Adjacent sequences: A071121 A071122 A071123 * A071125 A071126 A071127

Keyword

nonn

Author

Labos Elemer, May 29 2002

Status

approved