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A077682
Squarefree numbers beginning with 6.
12
6, 61, 62, 65, 66, 67, 69, 601, 602, 606, 607, 609, 610, 611, 613, 614, 615, 617, 618, 619, 622, 623, 626, 627, 629, 631, 633, 634, 635, 638, 641, 642, 643, 645, 646, 647, 649, 651, 653, 654, 655, 658, 659, 661, 662, 663, 665, 667, 669, 670, 671, 673, 674
OFFSET
1,1
COMMENTS
Intersection of A005117 and A217399. - Michel Marcus, Sep 14 2013
Lower density is 1/(10*Pi^2), upper density is 20/(21*Pi^2). - Charles R Greathouse IV, Nov 05 2017
LINKS
MAPLE
with(numtheory): select(issqrfree, [seq(seq(6*10^n+k, k=0..10^n-1), n=0..3)]); # Muniru A Asiru, Nov 22 2018
MATHEMATICA
Select[Range[1000], SquareFreeQ[#]&&First[IntegerDigits[#]]==6&] Harvey P. Dale, May 19 2012
PROG
(PARI) is(n)=n>5 && digits(n)[1]==6 && issquarefree(n) \\ Charles R Greathouse IV, Nov 05 2017
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 16 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 28 2003
STATUS
approved