863820

Appears in sequences

• a(n) = 2^n - binomial(n, floor(n/2)).at n=20A045621
• a(n) = 4^n - binomial(2*n,n).at n=10A068551
• Number of n X 2 0..1 arrays with row sums equal and column sums unequal to adjacent columns.at n=19A202736
• Even-indexed terms of A247984, a sequence motivated by generalized quadrangles.at n=9A246800
• Constant terms of congruences derived from a permutation polynomial motivated by generalized quadrangles.at n=19A247984
• Number of n-step random walks on a line starting from the origin and returning to it at least once.at n=20A307768