20419

Appears in sequences

• Related to population of numbers of form x^2 + y^2.at n=16A000694
• Number of fib101 primes (A095089) in range ]2^n,2^(n+1)].at n=20A095069
• Semiprimes in A003215.at n=34A113530
• Number of triangles that can be built from rods with lengths 1,2,...,n by using and concatenating all rods.at n=41A160455
• Erroneous version of A271811 (but for odd primes only).at n=19A271664
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 537", based on the 5-celled von Neumann neighborhood.at n=27A272792
• Triangle read by rows: T(n,k) number of ways of partitioning the (n+4)-element multiset {1,1,1,1,1,2,3,...,n} into exactly k nonempty parts, n >= 0 and 1 <= k <= n + 4.at n=66A291119
• Number of aperiodic relatively prime trees with n nodes.at n=14A317708