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 A078977 #12 Apr 22 2025 14:08:06 %S A078977 1,1,19,134,153,287,3023,163529,2619487,2783016,5402503,105430573, %T A078977 9494154073,237459282398,246953436471,484412718869,13810509564803, %U A078977 1740608617884047,59194503517622401,60935112135506448 %N A078977 Denominator of n-th convergent to e^(2/3). %F A078977 Special cases : a(5k+1)=abs(A065923(3k)); a(5k+3)=abs(A065923(3k+2)) where A065923(n)=y(n, -3) where y(n, x)=sum (k=0, n, (n+k)!*(x/2)^k/((n-k)!*k!)) %t A078977 Denominator[Convergents[E^(2/3),20]] (* _Harvey P. Dale_, Dec 01 2013 *) %o A078977 (PARI) a(n)=component(component(contfracpnqn(contfrac(exp(2/3),n)),1),2) \\ (Warning: this will give only a limited number of correct terms, depending on the precision used. - The Editors, Oct 13 2009. See A078976 for better code.) %Y A078977 Cf. A069951, A065923, A001518, A007677, A078976. %K A078977 frac,nonn %O A078977 1,3 %A A078977 _Benoit Cloitre_, Dec 19 2002