612009

Appears in sequences

• Number of binary words of length n in which the ones occur only in blocks of length at least 4.at n=33A005253
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, -1), (0, 1, -1), (1, 0, 0), (1, 1, 1)}.at n=10A150497
• G.f.: 1/(1 - (1*x)/(1 - (2*x)^2/(1 - (3*x)^3/(1 - (4*x)^4/(1 - (5*x)^5/(1 - ...)))))).at n=12A343420
• Expansion of 1/(1 - x^2/(1-x)^5).at n=14A369803
• Expansion of (1 + x)/(1 - x^2*(1 + x)^3).at n=22A375315
• a(n) = Sum_{k=0..floor(2*n/5)} binomial(2*n-3*k,2*k).at n=17A391541