72870

Appears in sequences

• Numbers k having exactly 5 distinct prime factors, the largest of which is greater than or equal to sqrt(k) (i.e., sqrt(k)-rough numbers with exactly 5 distinct prime factors).at n=22A115959
• a(n) = 81n^2 - n.at n=29A157953
• a(n) = 324n^2 - 2n.at n=14A158305
• a(n) = 900*n^2 - 30.at n=8A158669
• Least positive integer k such that k and k*n are terms of A259539.at n=9A259540
• Least positive integer k such that k and k*n are terms of A259539.at n=29A259540
• Solution of the complementary equation a(n) = a(n-1) + a(n-3) + a(n-4) + b(n-1), where a(0) = 1, a(1) = 2, a(2) = 3, a(3) = 4, b(0) = 5, b(1) = 6, b(2) = 7, b(3) = 8, and (a(n)) and (b(n)) are increasing complementary sequences.at n=21A295757
• Triangle read by rows: T(n,k) = number of free hexagonal polyominoes with n cells, where the maximum number of cells on any lattice line is k. The term "lattice line" here means a line running through the cell centers and midpoints of their sides.at n=58A378014
• Expansion of 1/((1-x) * (1-9*x))^(5/2).at n=4A387313