2449868

Appears in sequences

• a(n) = 2^(n-1) + ((1 + (-1)^n)/4)*binomial(n, n/2).at n=22A027306
• a(n) = Sum_{i=0..n} binomial(2*n, i).at n=11A032443
• Expansion of ((1 + x - 2x^2) + (1+x)*sqrt(1-4x^2))/(2(1-4x^2)).at n=23A116406
• a(n) = Sum_{k=0..11} C(n, k).at n=22A219531
• Number of (n+2)X(5+2) 0..3 arrays with every 3X3 subblock row and column sum not equal to 0 2 4 6 or 7 and every 3X3 diagonal and antidiagonal sum equal to 0 2 4 6 or 7.at n=7A252520