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 A230724 #12 Oct 30 2013 13:24:41
%S A230724 0,0,1,1,2,4,7,4,6,8,9,14,13,9,18,13,13,26,16,19,25,15,14,18,20,34,36,
%T A230724 36,25,34,32,37,40,46,42,47,45,35,37,36,45,37,55,47,58,43,49,42,62,63,
%U A230724 41,58,45,63,67,76,71,43,73,70,60,86,63,83,61,72,99,88,61
%N A230724 Digital sum of tribonacci numbers with a(0)=a(1)=0, a(2)=1.
%H A230724 Irene Sermon, <a href="/A230724/b230724.txt">Table of n, a(n) for n = 0..10000</a>
%F A230724 a(n) = A007953(A000073(n)).
%e A230724 In the tribonacci series with initial terms a(0)=a(1)=0 and a(2)=1, the 30th term is 15902591. Its digital sum is 32.
%t A230724 t = LinearRecurrence[{1, 1, 1}, {0, 0, 1}, 60]; Total /@ IntegerDigits /@ t (* _T. D. Noe_, Oct 30 2013 *)
%Y A230724 Cf. A000073.
%K A230724 nonn,base
%O A230724 0,5
%A A230724 _Irene Sermon_, Oct 28 2013