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 A205505 #13 Nov 21 2013 12:50:22 %S A205505 1,8,72,2255,166408,33489287,17373187209,23735905327584, %T A205505 84707858657965180,792123204706451722511,19386236394149894806708656, %U A205505 1242293991563772001787883943693,208405704482555536994509895576090977,91533085042008706066658193727853843719640 %N A205505 Fibonacci(n*(n+1)) / Fibonacci(n). %F A205505 a(n) = [x^n] 1/(1 - Lucas(n)*x + (-1)^n*x^2), where Lucas(n) = A000204(n). %F A205505 Forms a diagonal in table A028412. %t A205505 Table[Fibonacci[n(n+1)]/Fibonacci[n],{n,20}] (* _Harvey P. Dale_, Mar 30 2012 *) %o A205505 (PARI) {a(n)=fibonacci(n*(n+1))/fibonacci(n)} %o A205505 (PARI) {Lucas(n)=fibonacci(n-1)+fibonacci(n+1)} %o A205505 {a(n)=polcoeff(1/(1-Lucas(n)*x+(-1)^n*x^2+x*O(x^n)), n)} %Y A205505 Cf. A103624, A051294, A028412. %K A205505 nonn,easy %O A205505 1,2 %A A205505 _Paul D. Hanna_, Jan 28 2012