A118669 Numbers that are not squarefree, but contain their squarefree kernel in decimal representation.

25, 32, 36, 96, 100, 125, 128, 162, 216, 243, 256, 300, 486, 512, 576, 625, 648, 700, 768, 864, 1000, 1024, 1100, 1215, 1296, 1300, 1536, 1700, 1900, 2048, 2100, 2300, 2430, 2900, 2916, 3000, 3100, 3125, 3300, 3456, 3700, 3773, 3900, 4100, 4300, 4608

Offset: 1

Author

Reinhard Zumkeller, May 19 2006

Keywords

• nonn
• base

Comments

For k>1: m*10^k are terms for squarefree numbers m coprime to 10.

If m is a term and coprime to 10 then also 10*m is a term.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Squarefree.

Crossrefs

Cf. A005117, A013929, A007947, A076333.

Programs

Mathematica

Select[Range[5000], (r = rad[#]) < # && SequenceCount @@ IntegerDigits[{#, r}] > 0 &] (* Amiram Eldar, Sep 07 2020 *)