A077677 Squarefree numbers beginning with 1.

1, 10, 11, 13, 14, 15, 17, 19, 101, 102, 103, 105, 106, 107, 109, 110, 111, 113, 114, 115, 118, 119, 122, 123, 127, 129, 130, 131, 133, 134, 137, 138, 139, 141, 142, 143, 145, 146, 149, 151, 154, 155, 157, 158, 159, 161, 163, 165, 166, 167, 170, 173, 174, 177

Offset

1,2

Comments

Intersection of A005117 and A131835. - Michel Marcus, Sep 14 2013

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

Cf. A077678, A077679, A077680, A077681, A077682, A077683, A077684, A077685.

Sequence in context: A171752 A058944 A167178 * A216502 A219256 A339076

Adjacent sequences: A077674 A077675 A077676 * A077678 A077679 A077680

Keyword

base,easy,nonn

Author

Amarnath Murthy, Nov 16 2002

Extensions

Corrected and extended by Sascha Kurz, Jan 28 2003

Status

approved