271961

Appears in sequences

• Numbers k such that 221*2^k+1 is prime.at n=43A032487
• Antidiagonal sums of A175105.at n=18A179807
• Triangle read by rows: T(n, k) = C(n, k)*Sum_{j=0..n} C(n, k-j)*C(n+j, j)/C(2*j, j).at n=51A339000