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 A020958 #11 Jul 08 2019 06:25:12
%S A020958 5,9,16,28,48,81,134,221,361,589,957,1554,2519,4082,6610,10702,17322,
%T A020958 28035,45368,73415,118795,192223,311031,503268,814313,1317596,2131924,
%U A020958 3449536,5581476,9031029,14612522,23643569,38256109,61899697,100155825,162055542,262211387
%N A020958 a(n) = Sum_{k >= 1} floor(3*tau^(n-k)).
%C A020958 Since 3*tau^(-3) < 1 the number of nonzero terms in the sum is finite. - _Giovanni Resta_, Jul 08 2019
%H A020958 C. Kimberling, <a href="https://www.jstor.org/stable/2975195">Problem 10520</a>, Amer. Math. Mon. 103 (1996) p. 347.
%F A020958 a(n) = Sum_{k=-2..(n-1)} floor(3*tau^k). - _Giovanni Resta_, Jul 08 2019
%t A020958 a[n_] := Sum[Floor[3 GoldenRatio^k], {k, -2, n-1}]; Array[a, 37] (* _Giovanni Resta_, Jul 08 2019 *)
%Y A020958 Cf. A001622 (tau), A020957.
%K A020958 nonn
%O A020958 1,1
%A A020958 _Clark Kimberling_
%E A020958 Name edited by _Michel Marcus_, Jul 06 2019
%E A020958 a(27)-a(37) from _Giovanni Resta_, Jul 08 2019