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 A014484 #16 Jul 08 2025 05:39:52 %S A014484 1,10,112,1440,21120,349440,6451200,131604480,2941747200,71530905600, %T A014484 1880240947200,53137244160000,1606870263398400,51776930709504000, %U A014484 1771128112545792000,64103411041173504000 %N A014484 Expansion of (1+2x)/(1-2x)^4 (E.g.f.). %H A014484 Robert Israel, <a href="/A014484/b014484.txt">Table of n, a(n) for n = 0..400</a> %F A014484 a(n) = (n+1)(n+2)(2n+3)/6 * 2^n * n!. - _Ralf Stephan_, Mar 24 2004 %F A014484 Conjecture: a(n) +(-2*n-9)*a(n-1) +6*(n+1)*a(n-2)=0. - _R. J. Mathar_, Jun 11 2013 %F A014484 Conjecture verified by _Robert Israel_, Jul 11 2018 %p A014484 seq((n+1)*(n+2)*(2*n+3)/6 * 2^n * n!, n=0..30); # _Robert Israel_, Jul 11 2018 %o A014484 (PARI) a(n)=(n+1)*(n+2)*(2*n+3)/6*2^n*n! \\ _Charles R Greathouse IV_, Jun 11 2013 %Y A014484 Cf. A006157. %K A014484 nonn,easy %O A014484 0,2 %A A014484 _N. J. A. Sloane_