3312554

Appears in sequences

• a(0)=0, a(1)=2 then a(n) = a(n-2) + 2*sqrt(8*a(n-1)^2 + 8*a(n-1) + 1).at n=9A053141
• a(n) = (2*Pell(n+1) - (1+(-1)^n))/4.at n=18A105635
• Expansion of (1-3*x) / (1-5*x-5*x^2+x^3).at n=9A108475
• Expansion of (1-x)/((1-x)^2 - x^2*(1+x)^2).at n=18A116404
• Sum of the altitudes of the leftmost valleys of all Dyck paths of semilength n (if path has no valley, then this altitude is taken to be 0).at n=14A143955