OFFSET
1,2
COMMENTS
Lower density is 3/(5*Pi^2), upper density is 10/(3*Pi^2). - Charles R Greathouse IV, Nov 05 2017
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[177], First[IntegerDigits[#]]==1 && SquareFreeQ[#] &] (* Jayanta Basu, May 23 2013 *)
PROG
(PARI) is(n)=n>0 && digits(n)[1]==1 && issquarefree(n) \\ Charles R Greathouse IV, Nov 05 2017
(PARI) list(lim)=my(v=List([1])); for(d=1, #Str(lim\=1)-1, my(D=10^d); forsquarefree(n=D, min(2*D, lim), listput(v, n[1]))); Vec(v) \\ Charles R Greathouse IV, Jan 10 2023
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 16 2002
EXTENSIONS
Corrected and extended by Sascha Kurz, Jan 28 2003
STATUS
approved