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A077685
Squarefree numbers beginning with 9.
12
91, 93, 94, 95, 97, 901, 902, 903, 905, 906, 907, 910, 911, 913, 914, 915, 917, 919, 921, 922, 923, 926, 929, 930, 933, 934, 935, 937, 938, 939, 941, 942, 943, 946, 947, 949, 951, 953, 955, 957, 958, 959, 962, 965, 966, 967, 969, 970, 971, 973, 974, 977, 978
OFFSET
1,1
COMMENTS
Intersection of A005117 and A217402. - Michel Marcus, Sep 14 2013
Lower density is 1/(15*Pi^2), upper density is 2/(3*Pi^2). - Charles R Greathouse IV, Nov 05 2017
LINKS
MATHEMATICA
Select[Range[1000], SquareFreeQ[#]&&First[IntegerDigits[#]]==9&] (* Harvey P. Dale, Dec 15 2013 *)
PROG
(PARI) isok(n) = issquarefree(n) && (digits(n)[1] == 9); \\ Michel Marcus, Sep 14 2013
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 16 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 28 2003
STATUS
approved