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 A048474 #22 Sep 08 2022 08:44:57
%S A048474 1,4,13,37,97,241,577,1345,3073,6913,15361,33793,73729,159745,344065,
%T A048474 737281,1572865,3342337,7077889,14942209,31457281,66060289,138412033,
%U A048474 289406977,603979777,1258291201,2617245697,5435817985
%N A048474 a(n) = 3*n*2^(n-1) + 1.
%C A048474 Original name: a(n) = T(2, n), array T given by A048472.
%C A048474 Binomial transform of A008486. - _Paul Barry_, Jul 09 2003
%C A048474 Row sums of triangle A134232. - _Gary W. Adamson_, Oct 14 2007
%H A048474 Vincenzo Librandi, <a href="/A048474/b048474.txt">Table of n, a(n) for n = 0..1000</a>
%H A048474 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (5, -8, 4).
%F A048474 From _Harvey P. Dale_, Jan 29 2012: (Start)
%F A048474 a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3); a(0)=1, a(1)=4, a(2)=13.
%F A048474 G.f.: (-x^2 + x - 1)/((x-1)(2*x-1)^2). (End)
%t A048474 Table[3n 2^(n-1)+1,{n,0,30}] (* or *) LinearRecurrence[{5,-8,4},{1,4,13},30] (* _Harvey P. Dale_, Jan 29 2012 *)
%o A048474 (Magma) [3*n * 2^(n-1) + 1: n in [0..30]]; // _Vincenzo Librandi_, Sep 23 2011
%o A048474 (PARI) a(n)=3*n*2^(n-1)+1 \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A048474 n-th difference of a(n), a(n-1), ..., a(0) is (3, 6, 9, ...).
%Y A048474 Cf. A134232.
%K A048474 nonn,easy
%O A048474 0,2
%A A048474 _Clark Kimberling_
%E A048474 Better description from _Paul Barry_, Jul 09 2003