A203580 - cp's OEIS frontend

A203580 a(n) = Sum{d(i)2^i: i=0,1,...,m}, where Sum{d(i)7^i: i=0,1,...,m}=n, d(i)∈{0,1,...,6}.

%I A203580 #25 Jun 02 2025 07:36:43
%S A203580 0,1,2,3,4,5,6,2,3,4,5,6,7,8,4,5,6,7,8,9,10,6,7,8,9,10,11,12,8,9,10,
%T A203580 11,12,13,14,10,11,12,13,14,15,16,12,13,14,15,16,17,18,4,5,6,7,8,9,10,
%U A203580 6,7,8,9,10,11,12,8,9,10,11,12,13,14,10,11,12,13,14
%N A203580 a(n) = Sum{d(i)*2^i: i=0,1,...,m}, where Sum{d(i)*7^i: i=0,1,...,m}=n, d(i)∈{0,1,...,6}.
%C A203580 Change-of-base sequence 7->2.
%H A203580 Clark Kimberling, <a href="/A203580/b203580.txt">Table of n, a(n) for n = 0..1000</a>
%F A203580 a(0)=0, a(n)=2*a(n/7) if n==0 (mod 7), a(n)=a(n-1)+1 otherwise.
%t A203580 t = Table[FromDigits[RealDigits[n, 7], 2], {n, 0, 100}] (* _Clark Kimberling_, Aug 03 2012 *)
%Y A203580 Cf. A033044.
%K A203580 nonn,base
%O A203580 0,3
%A A203580 _Karol Bacik_, Jan 03 2012

cp's OEIS Frontend

A203580 a(n) = Sum{d(i)*2^i: i=0,1,...,m}, where Sum{d(i)*7^i: i=0,1,...,m}=n, d(i)∈{0,1,...,6}.

A203580 a(n) = Sum{d(i)2^i: i=0,1,...,m}, where Sum{d(i)7^i: i=0,1,...,m}=n, d(i)∈{0,1,...,6}.