2555756

Appears in sequences

• a(n) = a(n-1)+a(n-2)+a(n-3)+2 with a(0)=0, a(1)=0 and a(2)=1.at n=25A089068
• Diagonal sums of Riordan array (1/(1+x),x(1+x)/(1-x)).at n=27A112476