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 A378278 #4 Nov 21 2024 16:05:36 %S A378278 1,0,0,0,1,1,3,7,15,27,51,99,199,403,819,1651,3303,6579,13107,26163, %T A378278 52327,104755,209715,419635,839271,1678131,3355443,6710067,13420135, %U A378278 26841907,53687091,107377459,214754919,429503283,858993459,1717973811,3435947623 %N A378278 Cogrowth sequence of the 20-element Frobenius group Frob20 = <S,T | S^5, T^4, (ST)^4>. %F A378278 G.f.: (x^6+x^4+x^3-3*x^2+3*x-1) / ((2*x-1) * (x+1) * (x^2+1)/(2*x^2-2*x+1)). %Y A378278 Cf. A078789 (D10), A378254 (C10 X C2), A378276 (Dic20). %K A378278 nonn,easy %O A378278 0,7 %A A378278 _Sean A. Irvine_, Nov 21 2024