19883

Appears in sequences

• Numbers that are the product of two distinct primes and they are partial sum of products of two distinct primes.at n=31A168476
• Number of n X 3 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.at n=8A197368
• T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,4,1,0,1 for x=0,1,2,3,4.at n=57A197373
• Consider a number x. Take the sum of its digits. Repeat the process deleting the first addendum and adding the previous sum. The sequence lists the numbers that after some iterations reach the arithmetic derivative of x.at n=21A269312
• Smallest number that is the sum of n successive primes and also the sum of n successive semiprimes, n > 1.at n=37A283873
• a(n) = Sum_{k=0..floor(n/4)} binomial(n-3*k,k) * Catalan(n-3*k).at n=10A360272
• Semiprimes of the form k^2 + 2.at n=39A360739