20381

Appears in sequences

• Difference between the sum of next prime(n) natural numbers and the sum of next n primes.at n=20A082749
• Sum of all terms on the two principal diagonals of a 2n+1 X 2n+1 square spiral.at n=15A114254
• The sum of the principal diagonals of an n X n spiral.at n=31A137930
• Number of partitions p of n such that max(p) - min(p) = 10.at n=39A218573
• a(n) = Sum_{i=0..n} digsum_7(i)^4, where digsum_7(i) = A053828(i).at n=25A231679
• Number of Hamiltonian cycles in a tournament on 3n vertices constructed by taking 3 copies of a transitive tournament on n vertices and placing each copy on a vertex of a directed 3-cycle, with all edges between the copies oriented in the direction of the cycle.at n=3A256286
• Numbers k such that both k and k+2 are de Polignac numbers (A006285).at n=32A330284