A179579 - OEIS

%I #11 Jan 11 2017 18:25:38

%S 37,73,142,276,539,1059,2092,4150,8257,16461,32858,65640,131191,

%T 262279,524440,1048746,2097341,4194513,8388838,16777468,33554707,

%U 67109163,134218052,268435806,536871289,1073742229,2147484082,4294967760

%N Number of permutations of 1..n+4 with the number moved left exceeding the number moved right by n or more.

%C Recurrence would also extend to an a(0) if the definition were made to exclude the identity permutation.

%H R. H. Hardin, <a href="/A179579/b179579.txt">Table of n, a(n) for n=1..100</a>

%F Empirical: a(n)=5*a(n-1)-9*a(n-2)+7*a(n-3)-2*a(n-4) ; G.f.: -x*(-37+112*x-110*x^2+36*x^3) / ( (2*x-1)*(x-1)^3 ).

%F Empirical: a(n) = (n+4)*(n+1)/2+2^(n+4). - _R. J. Mathar_, May 26 2016

%K nonn

%O 1,1

%A _R. H. Hardin_, g.f. from _R. J. Mathar_ in the Sequence Fans Mailing List, Jul 19 2010