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 A108153 #21 Nov 22 2024 12:43:20
%S A108153 0,1,3,11,40,145,526,1908,6921,25105,91065,330326,1198213,4346356,
%T A108153 15765820,57188385,207443151,752472043,2729490816,9900859685,
%U A108153 35914032730,130273308376,472548850273,1714107200301,6217692609825,22553841080350,81811015661001
%N A108153 a(n) = 3*a(n-1) + 2*a(n-2) + a(n-3).
%H A108153 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,2,1).
%F A108153 G.f.: x/(1-3*x-2*x^2-x^3). [_R. J. Mathar_, Mar 19 2009]
%F A108153 a(n) = 11*a(n-2) +7*a(n-3)+3*a(n-4). [_Gary Detlefs_, Sep 13 2010]
%t A108153 M = {{0, 1, 0}, {0, 0, 1}, {1, 2, 3}} a3 = Table[MatrixPower[M, i][[1, 3]], {i, 1, 50}]
%t A108153 LinearRecurrence[{3,2,1},{0,1,3},40] (* _Vladimir Joseph Stephan Orlovsky_, Jan 31 2012 *)
%t A108153 nxt[{a_,b_,c_}]:={b,c,a+2b+3c}; NestList[nxt,{0,1,3},30][[;;,1]] (* _Harvey P. Dale_, Nov 22 2024 *)
%Y A108153 Cf. A000073, A001590. Essentially the same as A010911.
%K A108153 nonn,easy
%O A108153 0,3
%A A108153 _Roger L. Bagula_, Jun 06 2005
%E A108153 Definition replaced by the Adamson recurrence - the Associate Editors of the OEIS, Sep 28 2009