A077682 - OEIS

A077682

Squarefree numbers beginning with 6.

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

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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

Muniru A Asiru, Table of n, a(n) for n = 1..6761

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

CROSSREFS

Cf. A077677, A077678, A077679, A077680, A077681, A077683, A077684, A077685.

Sequence in context: A075069 A324200 A335733 * A326739 A055331 A024523

Adjacent sequences: A077679 A077680 A077681 * A077683 A077684 A077685

KEYWORD

base,easy,nonn

AUTHOR

Amarnath Murthy, Nov 16 2002

EXTENSIONS

More terms from Sascha Kurz, Jan 28 2003

STATUS

approved