A179579 Number of permutations of 1..n+4 with the number moved left exceeding the number moved right by n or more.

37, 73, 142, 276, 539, 1059, 2092, 4150, 8257, 16461, 32858, 65640, 131191, 262279, 524440, 1048746, 2097341, 4194513, 8388838, 16777468, 33554707, 67109163, 134218052, 268435806, 536871289, 1073742229, 2147484082, 4294967760

Offset

1,1

Comments

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

Links

R. H. Hardin, Table of n, a(n) for n=1..100

Formula

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 ).

Empirical: a(n) = (n+4)*(n+1)/2+2^(n+4). - R. J. Mathar, May 26 2016

Crossrefs

Sequence in context: A039420 A043243 A044023 * A069204 A153208 A128388

Adjacent sequences: A179576 A179577 A179578 * A179580 A179581 A179582

Keyword

nonn

Author

R. H. Hardin, g.f. from R. J. Mathar in the Sequence Fans Mailing List, Jul 19 2010

Status

approved