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Multiples of 7 in base 8.
5

%I #23 Feb 28 2019 05:01:25

%S 7,16,25,34,43,52,61,70,77,106,115,124,133,142,151,160,167,176,205,

%T 214,223,232,241,250,257,266,275,304,313,322,331,340,347,356,365,374,

%U 403,412,421,430,437,446,455,464,473,502,511,520,527,536,545,554,563

%N Multiples of 7 in base 8.

%C Digit sum is always divisible by 7.

%C Reinterpreting this sequence in base 10, these are numbers of the form 9n + 7 but with all numbers containing 8s and/or 9s removed. - _Alonso del Arte_, Sep 23 2012

%F a(n) = A007094(A008589(n)). -

%e a(10) = 106 because 7 * 10 = 70, or 1 * 8^2 + 0 * 8^1 + 6 * 8^0 = 64 + 6 = 106_8.

%t Table[BaseForm[7*n, 8], {n, 100}] (* _Alonso del Arte_, Sep 23 2012 *)

%t Select[9*Range[0, 99] + 7, DigitCount[#, 10, 8] == 0 && DigitCount[#, 10, 9] == 0 &] (* _Alonso del Arte_, Sep 23 2012 *)

%t Table[FromDigits[IntegerDigits[7*n, 8]], {n, 100}] (* _T. D. Noe_, Sep 24 2012 *)

%o (JavaScript)

%o k = 7;

%o for (i = 1; i <= 200; i++) {

%o x = i * k;

%o document.write(x.toString(k + 1) + ", ");

%o }

%Y Cf. A216994, A216995, A216996, A216997, A216998.

%Y Cf. A008589.

%K nonn,base,easy

%O 1,1

%A _Jon Perry_, Sep 23 2012