21413

Appears in sequences

• Row sums of triangle A137639.at n=35A137640
• a(1) = 1; thereafter a(n) is always the smallest integer > a(n-1) not leading to a contradiction, such that any five consecutive digits in the sequence sum up to a prime.at n=40A152605
• Total number of parts that are the smallest part or the largest part in all partitions of n.at n=27A182978
• Number of partitions of n such that 2*(greatest part) > (number of parts).at n=37A237754
• Number of nX3 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.at n=6A240402
• T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.at n=38A240406
• T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.at n=42A240406
• Composite numbers k such that sigma(k + sigma(k)) = 2*sigma(k).at n=25A246858
• Numbers k such that k is the uphi(k)-th composite number, where uphi is the unitary totient function.at n=14A300479
• Numbers that are the sum of eight fourth powers in nine or more ways.at n=22A345584
• Numbers that are the sum of eight fourth powers in ten or more ways.at n=11A345585
• Numbers that are the sum of eight fourth powers in exactly ten ways.at n=8A345842
• Numbers k that divide the k-th Apéry number (A005258).at n=20A372943