70847

Appears in sequences

• a(n) = Sum_{k=0..floor(n/4)} C(n-2*k,2*k)*2^k.at n=21A098575
• Triangle read by rows: T(n,k) is the number of bargraphs of semiperimeter n having k levels. A level in a bargraph is a maximal sequence of two or more adjacent horizontal steps; it is preceded and followed by either an up step or a down step.at n=57A273344
• Squares where A323809 gets stuck.at n=30A323813
• a(n) = Sum_{k=0..floor(n/2)} 2^k * binomial(2*n-2*k+1,2*k).at n=10A387624