A077684 - OEIS

A077684

Squarefree numbers with 8 as their initial (leftmost) digit.

82, 83, 85, 86, 87, 89, 802, 803, 805, 806, 807, 809, 811, 813, 814, 815, 817, 818, 821, 822, 823, 826, 827, 829, 830, 831, 834, 835, 838, 839, 842, 843, 849, 851, 853, 854, 857, 858, 859, 861, 862, 863, 865, 866, 869, 870, 871, 874, 877, 878, 879, 881, 883

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OFFSET

1,1

COMMENTS

Intersection of A005117 and A217401. - Michel Marcus, Sep 14 2013

Lower density is 3/(40*Pi^2), upper density is 20/(27*Pi^2). - Charles R Greathouse IV, Nov 05 2017

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[900], SquareFreeQ[#]&&First[IntegerDigits[#]]==8&] (* Harvey P. Dale, Feb 22 2011 *)

PROG

(PARI) is(n)=n>81 && digits(n)[1]==8 && issquarefree(n) \\ Charles R Greathouse IV, Nov 05 2017