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 A362316 #32 Sep 01 2023 04:31:54
%S A362316 0,0,4,18,64,210,664,2058,6304,19170,58024,175098,527344,1586130,
%T A362316 4766584,14316138,42981184,129009090,387158344,1161737178,3485735824,
%U A362316 10458256050,31376865304,94134790218,282412759264,847255055010,2541798719464,7625463267258,22876524019504,68629840493970
%N A362316 Expansion of e.g.f (exp(x)-1)*(exp(2*x)-1).
%C A362316 Number of ternary strings with at least one 0 or one 1 and at least one 2.
%H A362316 Paolo Xausa, <a href="/A362316/b362316.txt">Table of n, a(n) for n = 0..1000</a>
%H A362316 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-11,6).
%F A362316 a(n) = 3^n - 2^n - 1, n>0; a(0)=0.
%F A362316 a(n) = 2*A053152(n).
%e A362316 The 4 strings for n=4 are 12, 21, 02, 20.
%t A362316 LinearRecurrence[{6,-11,6},{0,0,4,18},30] (* _Paolo Xausa_, Aug 07 2023 *)
%Y A362316 Cf. A001550, A053152, A083321 (alternates signs).
%K A362316 nonn,easy
%O A362316 0,3
%A A362316 _Enrique Navarrete_, Apr 16 2023