OFFSET
1,4
LINKS
B. Nakamura, Approaches for enumerating permutations with a prescribed number of occurrences of patterns, arXiv 1301.5080, 2013.
Index entries for linear recurrences with constant coefficients, signature (8, -24, 32, -16).
FORMULA
a(n) = 2^(-8+n)*(-136+70*n-11*n^2+n^3) for n>3. G.f.: -x^4*(x^3-10*x^2+8*x-2) / (2*x-1)^4. - Colin Barker, Apr 14 2013
MAPLE
# Programs can be obtained from author's personal website.
MATHEMATICA
LinearRecurrence[{8, -24, 32, -16}, {0, 0, 0, 2, 8, 26, 79}, 40] (* Harvey P. Dale, Jun 23 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Brian Nakamura, Apr 03 2013
STATUS
approved