OFFSET
0,2
COMMENTS
a(base,n)=a(base-1,n)+5^(n-1) for base>=2n-1; a(base,n)=a(base-1,n)+5^(n-1)-2 when base=2n-2.
LINKS
S. Kitaev, J. Remmel, (a,b)-rectangle patterns in permutations and words, arXiv:1304.4286 [math.CO]
Index entries for linear recurrences with constant coefficients, signature (4,0,-1).
FORMULA
a(n) = 4*a(n-1)-a(n-3). G.f.: -(x^2-x-1)/(x^3-4*x+1). [Colin Barker, Nov 25 2012]
MATHEMATICA
LinearRecurrence[{4, 0, -1}, {1, 5, 19}, 30] (* Harvey P. Dale, Apr 27 2018 *)
PROG
(S/R) stvar $[N]:(0..M-1) init $[]:=0 asgn $[]->{*} kill +[i in 0..N-2](($[i]`-$[i+1]`>2)+($[i+1]`-$[i]`>2))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
R. H. Hardin, Dec 28 2006
EXTENSIONS
Edited by Charles R Greathouse IV, Aug 05 2010
STATUS
approved