A077680 - OEIS

A077680

Squarefree numbers beginning with 4.

41, 42, 43, 46, 47, 401, 402, 403, 406, 407, 409, 410, 411, 413, 415, 417, 418, 419, 421, 422, 426, 427, 429, 430, 431, 433, 434, 435, 437, 438, 439, 442, 443, 445, 446, 447, 449, 451, 453, 454, 455, 457, 458, 461, 462, 463, 465, 466, 467, 469, 470, 471, 473

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Lower density is 3/(20*Pi^2), upper density is 4/(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[499], First[IntegerDigits[#]]==4&&SquareFreeQ[#]&] (* Harvey P. Dale, Apr 24 2018 *)

PROG

(PARI) is(n)=n>40 && digits(n)[1]==4 && issquarefree(n) \\ Charles R Greathouse IV, Nov 05 2017

CROSSREFS