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 A026841 #13 Jul 22 2025 13:35:38
%S A026841 1,11,79,471,2535,12809,62067,292085,1345718,6102780,27343148,
%T A026841 121359692,534632836,2341151646,10201950700,44278673806,191540714294,
%U A026841 826265471868,3555992623850,15273547250820,65491352071266,280412963707416
%N A026841 a(n) = T(2n,n-4), T given by A026725.
%C A026841 Column k=10 of triangle A236830. - _Philippe Deléham_, Feb 02 2014
%H A026841 G. C. Greubel, <a href="/A026841/b026841.txt">Table of n, a(n) for n = 4..1000</a>
%F A026841 a(n) = A026848(n). - _Philippe Deléham_, Feb 02 2014
%F A026841 G.f.: (x^4*C(x)^10)/(1-x*C(x)^3) where C(x) is the g.f. of A000108. - _Philippe Deléham_, Feb 02 2014
%F A026841 D-finite with recurrence (n+4)*(3421*n+2687)*a(n) +(3421*n^2-245139*n-819238)*a(n-1) +3*(-126201*n^2+820641*n+1451992)*a(n-2) +(1944367*n^2-12105285*n+5094446)*a(n-3) +6*(-438489*n^2+3204217*n-6453730)*a(n-4) -12*(2*n-7)*(30601*n-111490)*a(n-5)=0. - _R. J. Mathar_, Jul 22 2025
%t A026841 Drop[CoefficientList[Series[(1-Sqrt[1-4*x])^10/(128*x^4*(8*x^2 -(1 - Sqrt[1-4*x])^3 )), {x,0,40}], x], 4] (* _G. C. Greubel_, Jul 17 2019 *)
%o A026841 (PARI) my(x='x+O('x^40)); Vec((1-sqrt(1-4*x))^10/(128*x^4*(8*x^2 -(1 - sqrt(1-4*x))^3 ))) \\ _G. C. Greubel_, Jul 17 2019
%o A026841 (Magma) R<x>:=PowerSeriesRing(Rationals(), 40); Coefficients(R!( (1-Sqrt(1-4*x))^10/(128*x^4*(8*x^2 -(1-Sqrt(1-4*x))^3 )) )); // _G. C. Greubel_, Jul 17 2019
%o A026841 (Sage) a=((1-sqrt(1-4*x))^10/(128*x^4*(8*x^2 -(1-sqrt(1-4*x))^3 ))).series(x, 45).coefficients(x, sparse=False); a[4:40] # _G. C. Greubel_, Jul 17 2019
%Y A026841 Cf. A236830.
%K A026841 nonn
%O A026841 4,2
%A A026841 _Clark Kimberling_