61053

Appears in sequences

• Number of partitions of n if there are two kinds of 1's and two kinds of 2's.at n=29A000097
• Number of arrangements of 4 numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero.at n=36A188359
• G.f.: Sum_{n>=0} x^n * (1+x)^A003188(n), where A003188(n) = n XOR [n/2] is the Gray code for n.at n=21A227526