A077681 Squarefree numbers beginning with 5.

5, 51, 53, 55, 57, 58, 59, 501, 502, 503, 505, 506, 509, 510, 511, 514, 515, 517, 518, 519, 521, 523, 526, 527, 530, 533, 534, 535, 537, 538, 541, 542, 543, 545, 546, 547, 551, 553, 554, 555, 557, 559, 561, 562, 563, 565, 566, 569, 570, 571, 573, 574, 577

Offset: 1

Author

Amarnath Murthy, Nov 16 2002

Keywords

• base
• easy
• nonn

Comments

Lower density is 3/(25*Pi^2), upper density is 10/(9*Pi^2). - Charles R Greathouse IV, Nov 05 2017

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..5000

Crossrefs

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

Programs

Mathematica

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

PARI

is(n)=n>4 && digits(n)[1]==5 && issquarefree(n) \\ Charles R Greathouse IV, Nov 05 2017

Extensions

More terms from Sascha Kurz, Jan 28 2003