OFFSET
0,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..925
S. Kitaev, Multi-avoidance of generalized patterns, Discrete Math., 260 (2003), 89-100.
MAPLE
with(combinat): a := array(0..50): a[0] := 1: a[1] := 1: for n from 2 to 50 do: a[n] := 0: for i from 0 to floor((n-1)/2.) do: a[n] := a[n]+binomial(n-i-1, i)*a[n-2*i-1]: od:a[n] := a[n]+((n+1) mod 2): od:seq(a[n], n=0..50);
MATHEMATICA
a[0] = a[1] = 1; a[n_] := a[n] = Sum[ Binomial[n - i - 1, i]*a[n - 2i - 1], {i, 0, Floor[n/2]}] + Mod[n + 1, 2]; Table[a[n], {n, 0, 30}]
PROG
(PARI) {a(n) = sum(j=0, floor(n/2), binomial(n-j-1, j)*a(n-2*j-1)) + lift(Mod(n+1, 2))};
vector(30, n, n--; if(n==0 && n==1, 1, a(n))) \\ G. C. Greubel, Jan 17 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
N. J. A. Sloane, Jan 21 2003
EXTENSIONS
More terms from Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 22 2003
STATUS
approved