20446

Appears in sequences

• Numbers k such that k*2^m+1 are composites for all exponents m in the range 0<=m<=k.at n=37A061153
• Denominators of convergents to Pi by Farey fractions.at n=48A063673
• Centered 47-gonal numbers.at n=29A129428
• Number of (2+1) X (n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.at n=9A250784
• G.f.: 1/((1-t^11)^2*(1-t)*(1-t^3)*(1-t^5)*(1-t^7)*(1-t^9)*(1-t^13)*(1-t^15)*(1-t^17)*(1-t^19)*(1-t^21)).at n=66A266751
• Least number that is the start of a gap of size n between numbers that are either prime or twice a prime (A001751).at n=30A290572
• G.f. satisfies A(x) = 1 + x*A(x)^4*(1 - x).at n=7A367016
• Triangular array T(n,k), read by rows: coefficients of strong divisibility sequence of polynomials p(1,x) = 1, p(2,x) = 2 + 3*x, p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where u = p(2,x), v = 1 - 2*x - x^2.at n=38A367297