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

1,1

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.

Mathematica

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

Crossrefs

Cf. A005117, A013929, A007947, A076333.

Sequence in context: A043146 A043926 A202000 * A092100 A172007 A107258

Adjacent sequences: A118666 A118667 A118668 * A118670 A118671 A118672

Keyword

nonn,base

Author

Reinhard Zumkeller, May 19 2006

Status

approved