cp's OEIS Frontend

A303789 a(n) = Sum_{i=0..m} d(i)*6^i, where Sum_{i=0..m} d(i)*7^i is the base-7 representation of n.

%I A303789 #34 Jun 29 2019 01:39:12
%S A303789 0,1,2,3,4,5,6,6,7,8,9,10,11,12,12,13,14,15,16,17,18,18,19,20,21,22,
%T A303789 23,24,24,25,26,27,28,29,30,30,31,32,33,34,35,36,36,37,38,39,40,41,42,
%U A303789 36,37,38,39,40,41,42,42,43,44,45,46,47,48,48,49,50,51,52,53,54,54,55
%N A303789 a(n) = Sum_{i=0..m} d(i)*6^i, where Sum_{i=0..m} d(i)*7^i is the base-7 representation of n.
%H A303789 Seiichi Manyama, <a href="/A303789/b303789.txt">Table of n, a(n) for n = 0..10000</a>
%e A303789 19 = 25_7, so a(19) = 2*6 + 5 = 17.
%e A303789 20 = 26_7, so a(20) = 2*6 + 6 = 18.
%e A303789 21 = 30_7, so a(21) = 3*6 + 0 = 18.
%e A303789 22 = 31_7, so a(22) = 3*6 + 1 = 19.
%o A303789 (Ruby)
%o A303789 def f(k, ary)
%o A303789   (0..ary.size - 1).inject(0){|s, i| s + ary[i] * k ** i}
%o A303789 end
%o A303789 def A(k, n)
%o A303789   (0..n).map{|i| f(k, i.to_s(k + 1).split('').map(&:to_i).reverse)}
%o A303789 end
%o A303789 p A(6, 100)
%o A303789 (PARI) a(n) = fromdigits(digits(n, 7), 6); \\ _Michel Marcus_, May 02 2018
%Y A303789 Sum_{i=0..m} d(i)*b^i, where Sum_{i=0..m} d(i)*(b+1)^i is the base (b+1) representation of n: A065361 (b=2), A215090 (b=3), A303787 (b=4), A303788 (b=5), this sequence (b=6).
%Y A303789 Cf. A037470.
%K A303789 nonn,base
%O A303789 0,3
%A A303789 _Seiichi Manyama_, Apr 30 2018