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 A375026 #5 Aug 07 2024 09:19:09 %S A375026 1,-3,6,-9,12,-18,30,-45,60,-90,156,-234,288,-432,846,-1269,1260, %T A375026 -1890,4980,-7470,3912,-5868,33996,-50994,-11688,17532,285720,-428580, %U A375026 -471480,707220,2950830,-4426245,-7902900,11854350,35254980,-52882470,-115143480,172715220,457385220 %N A375026 a(n) = [x^n] 2/(3*sqrt(4*x^2 + 1) + 6*x - 1). Alternating row sums of A375025. %p A375026 gf := 2/(3*sqrt(4*x^2 + 1) + 6*x - 1): %p A375026 ser := series(gf, x, 42): seq(coeff(ser, x, n), n = 0..38); %Y A375026 Cf. A375025. %K A375026 sign %O A375026 0,2 %A A375026 _Peter Luschny_, Aug 07 2024