A077679 - OEIS

A077679

Squarefree numbers beginning with 3.

3, 30, 31, 33, 34, 35, 37, 38, 39, 301, 302, 303, 305, 307, 309, 310, 311, 313, 314, 317, 318, 319, 321, 322, 323, 326, 327, 329, 330, 331, 334, 335, 337, 339, 341, 345, 346, 347, 349, 353, 354, 355, 357, 358, 359, 362, 365, 366, 367, 370, 371, 373, 374, 377

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OFFSET

1,1

COMMENTS

Intersection of A005117 and A217395. - Michel Marcus, Sep 14 2013

Lower density is 1/(5*Pi^2), upper density is 5/(3*Pi^2). - Charles R Greathouse IV, Nov 05 2017

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[400], SquareFreeQ[#]&&IntegerDigits[#][[1]]==3&] (* Harvey P. Dale, Oct 10 2018 *)

PROG

(PARI) isok(n) = (issquarefree(n) && (digits(n, 10)[1] == 3)) \\ Michel Marcus, Jul 31 2013