cp's OEIS Frontend

A217009 Multiples of 7 in base 8.

%I A217009 #23 Feb 28 2019 05:01:25
%S A217009 7,16,25,34,43,52,61,70,77,106,115,124,133,142,151,160,167,176,205,
%T A217009 214,223,232,241,250,257,266,275,304,313,322,331,340,347,356,365,374,
%U A217009 403,412,421,430,437,446,455,464,473,502,511,520,527,536,545,554,563
%N A217009 Multiples of 7 in base 8.
%C A217009 Digit sum is always divisible by 7.
%C A217009 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 A217009 a(n) = A007094(A008589(n)). -
%e A217009 a(10) = 106 because 7 * 10 = 70, or 1 * 8^2 + 0 * 8^1 + 6 * 8^0 = 64 + 6 = 106_8.
%t A217009 Table[BaseForm[7*n, 8], {n, 100}] (* _Alonso del Arte_, Sep 23 2012 *)
%t A217009 Select[9*Range[0, 99] + 7, DigitCount[#, 10, 8] == 0 && DigitCount[#, 10, 9] == 0 &] (* _Alonso del Arte_, Sep 23 2012 *)
%t A217009 Table[FromDigits[IntegerDigits[7*n, 8]], {n, 100}] (* _T. D. Noe_, Sep 24 2012 *)
%o A217009 (JavaScript)
%o A217009 k = 7;
%o A217009 for (i = 1; i <= 200; i++) {
%o A217009 x = i * k;
%o A217009 document.write(x.toString(k + 1) + ", ");
%o A217009 }
%Y A217009 Cf. A216994, A216995, A216996, A216997, A216998.
%Y A217009 Cf. A008589.
%K A217009 nonn,base,easy
%O A217009 1,1
%A A217009 _Jon Perry_, Sep 23 2012