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 A116454 #14 Sep 01 2025 17:36:35
%S A116454 0,2,9,25,59,129,271,557,1131,2281,4583,9189,18403,36833,73695,147421,
%T A116454 294875,589785,1179607,2359253,4718547,9437137,18874319,37748685,
%U A116454 75497419,150994889,301989831,603979717,1207959491,2415919041
%N A116454 Smallest m such that A116452(m) = n.
%C A116454 A116451(a(n)) = A116453(n);
%C A116454 Primes include a(2) = 2, a(5) = 59, a(7) = 271, a(8) = 557, a(10) = 2281, a(11) = 4583, a(14) = 36833. - _Jonathan Vos Post_, Feb 20 2006
%H A116454 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (4,-5,2).
%F A116454 a(n+1) = (a(n) + n) * 2 + 1 for n>1.
%F A116454 From _Harvey P. Dale_, Jul 18 2011: (Start)
%F A116454 a(0)=0, a(1)=2, a(2)=9, a(3)=25, a(n) = 4*a(n-1)-5*a(n-2)+2*a(n-3).
%F A116454 G.f.: (x-2)*x^2*(x+1)/((x-1)^2*(2*x-1)). (End)
%t A116454 Join[{0},RecurrenceTable[{a[1]==2,a[n]==2(a[n-1]+n)+1},a[n],{n,30}]] (* or *) Join[{0},LinearRecurrence[{4,-5,2},{2,9,25},30]] (* _Harvey P. Dale_, Jul 18 2011 *)
%K A116454 nonn,easy,changed
%O A116454 1,2
%A A116454 _Reinhard Zumkeller_, Feb 16 2006