OFFSET
1,1
COMMENTS
Lower density is 1/(10*Pi^2), upper density is 20/(21*Pi^2). - Charles R Greathouse IV, Nov 05 2017
LINKS
Muniru A Asiru, Table of n, a(n) for n = 1..6761
MAPLE
with(numtheory): select(issqrfree, [seq(seq(6*10^n+k, k=0..10^n-1), n=0..3)]); # Muniru A Asiru, Nov 22 2018
MATHEMATICA
Select[Range[1000], SquareFreeQ[#]&&First[IntegerDigits[#]]==6&] Harvey P. Dale, May 19 2012
PROG
(PARI) is(n)=n>5 && digits(n)[1]==6 && issquarefree(n) \\ Charles R Greathouse IV, Nov 05 2017
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 16 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 28 2003
STATUS
approved