This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A045670 #10 Jan 27 2020 15:14:51
%S A045670 1,2,3,2,3,4,3,4,5,4,5,6,3,4,5,4,5,6,5,6,7,4,5,6,5,6,7,6,7,8,5,6,7,6,
%T A045670 7,8,7,8,9,4,5,6,5,6,7,6,7,8,5,6,7,6,7,8,7,8,9,6,7,8,7,8,9,8,9,10,5,6,
%U A045670 7,6,7,8,7,8,9,6,7,8,7,8,9,8,9,10,7,8,9,8,9,10
%N A045670 Digital sum (in base 10) of numbers in base 3 of the alternate number system.
%C A045670 The alternate number system has no need for the digit zero.
%D A045670 Robert R. Forslund, A Logical Alternative to the Existing Positional Number System, Southwest Journal of Pure and Applied Mathematics. Vol. 1 1995 pp. 27-29.
%H A045670 Andrew Howroyd, <a href="/A045670/b045670.txt">Table of n, a(n) for n = 1..10000</a>
%H A045670 R. R. Forslund, <a href="http://www.emis.de/journals/SWJPAM/Vol1_1995/rrf01.ps">A logical alternative to the existing positional number system</a>, Southwest Journal of Pure and Applied Mathematics, 1995 Vol. 1.
%H A045670 R. R. Forslund, <a href="http://my.tbaytel.net/~forslund/index.html">Positive Integer Pages</a>
%H A045670 EMIS, <a href="http://www.emis.de/journals/SWJPAM/vol1-95.html">Mirror site for Southwest Journal of Pure and Applied Mathematics</a>
%F A045670 a(n) = A007953(A007932(n)). - _Andrew Howroyd_, Jan 27 2020
%o A045670 (PARI) a(n)={my(k=3); while(n>k, n-=k; k*=3); my(d=digits(n+k-1,3)); vecsum(d) + #d - 2} \\ _Andrew Howroyd_, Jan 27 2020
%Y A045670 Cf. A007931, A007932, A007953.
%K A045670 base,nonn
%O A045670 1,2
%A A045670 Bob Forslund (forslund(AT)tbaytel.net)
%E A045670 Terms a(25) and beyond from _Andrew Howroyd_, Jan 27 2020