27561

Appears in sequences

• Number of solutions to c(1)*prime(1) + ... + c(n)*prime(n) = 1, where c(i) = +-1 for i > 1, c(1) = 1.at n=23A022895
• Length of n-th string generated by a Kolakoski(9,1) rule starting with a(1)=1.at n=11A095344
• G.f.: Sum_{n>=0} Product_{k=1..n} (1 - (1-x)^(2*k-1))/(1 - x^(2*k-1)).at n=7A207653
• Floor(AGM(n^2, n^3)), where AGM denotes the arithmetic-geometric mean.at n=45A234362
• Composite numbers k such that phi(x) = psi(k)*phi(k) has no solution.at n=25A292714
• Positive integers m with m^k - 1 (k = 1,...,13) all practical.at n=21A294307
• Semiprimes of the form k^2 + 5.at n=46A361696
• Number of nonempty subsets of {1..n} with mean n/2.at n=21A362046
• a(0) = 2, thereafter a(n+1) is the nearest integer to 4*a(n)/3.at n=33A390254