A077681 - OEIS

%I #13 Nov 05 2017 01:43:50

%S 5,51,53,55,57,58,59,501,502,503,505,506,509,510,511,514,515,517,518,

%T 519,521,523,526,527,530,533,534,535,537,538,541,542,543,545,546,547,

%U 551,553,554,555,557,559,561,562,563,565,566,569,570,571,573,574,577

%N Squarefree numbers beginning with 5.

%C Lower density is 3/(25*Pi^2), upper density is 10/(9*Pi^2). - _Charles R Greathouse IV_, Nov 05 2017

%H Harvey P. Dale, <a href="/A077681/b077681.txt">Table of n, a(n) for n = 1..5000</a>

%t Table[Select[Range[5*10^n,6*10^n-1],SquareFreeQ],{n,0,2}]//Flatten (* _Harvey P. Dale_, Apr 15 2017 *)

%o (PARI) is(n)=n>4 && digits(n)[1]==5 && issquarefree(n) \\ _Charles R Greathouse IV_, Nov 05 2017

%Y Cf. A077677, A077678, A077679, A077680, A077682, A077683, A077684, A077685.

%K base,easy,nonn

%O 1,1

%A _Amarnath Murthy_, Nov 16 2002

%E More terms from _Sascha Kurz_, Jan 28 2003