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 A183245 #14 Mar 27 2018 08:49:17 %S A183245 9,29,112,436,1708,6724,26572,105316,418348,1664644,6632332,26450596, %T A183245 105566188,421556164,1684098892,6730018276,26900941228,107546369284, %U A183245 430013290252,1719536600356,6876596719468,27501737832004,109993004190412 %N A183245 Number of permutations of 1..2*n+2 with each element displaced by at least n. %C A183245 Row 3 of A183244. %H A183245 R. H. Hardin, <a href="/A183245/b183245.txt">Table of n, a(n) for n = 1..131</a> %F A183245 Empirical (for n>=2): 25*4^(n-2) + 4*3^(n-2). - _Vaclav Kotesovec_, Nov 27 2012 %F A183245 Conjectures from _Colin Barker_, Mar 27 2018: (Start) %F A183245 G.f.: x*(9 - 34*x + 17*x^2) / ((1 - 3*x)*(1 - 4*x)). %F A183245 a(n) = 7*a(n-1) - 12*a(n-2) for n>3. %F A183245 (End) %e A183245 All permutations of 1-6 with minimum displacement 2: %e A183245 (4,5,1,6,2,3) (4,5,1,6,3,2) (4,5,6,1,2,3) (4,5,6,1,3,2) (4,5,6,2,1,3) %e A183245 (4,5,6,2,3,1) (4,6,5,1,2,3) (4,6,5,1,3,2) (4,6,5,2,1,3) (4,6,5,2,3,1) %e A183245 (5,4,1,6,2,3) (5,4,1,6,3,2) (5,4,6,1,2,3) (5,4,6,1,3,2) (5,4,6,2,1,3) %e A183245 (5,4,6,2,3,1) (5,6,1,2,3,4) (3,4,5,6,1,2) (3,4,5,6,2,1) (3,5,1,6,2,4) %e A183245 (3,5,6,1,2,4) (3,5,6,2,1,4) (3,6,5,1,2,4) (3,6,5,2,1,4) (6,4,5,1,2,3) %e A183245 (6,4,5,1,3,2) (6,4,5,2,1,3) (6,4,5,2,3,1) (6,5,1,2,3,4) %Y A183245 Cf. A183244. %K A183245 nonn %O A183245 1,1 %A A183245 _R. H. Hardin_, Jan 03 2011