21689

Appears in sequences

• a(n) = (2*n - 5)n^2.at n=23A015240
• Numbers k such that 17^k - 16 is prime.at n=7A034922
• Numerators of row 4 of table described in A051714/A051715.at n=45A051722
• Number of positive terms in row n of A082268.at n=15A082269
• Numbers k such that the fractional part of (1024/1000)^k is greater than 1-(1/k).at n=11A153680
• Number of nX2 0..3 arrays with values 0..3 introduced in row major order, the number of instances of each value within one of each other, and every element equal to one or two horizontal or vertical neighbors.at n=9A199359
• Composites whose prime factorization in base 8 is an anagram of the number in base 8.at n=11A260052
• a(n) = greatest k such that A155043(k+A262509(n)) < A155043(A262509(n)).at n=40A262909
• Number of integer partitions of n with reverse-alternating product > 1.at n=41A347449
• Number of vertices formed in a square by straight line segments when connecting the n+1 points along each edge that divide it into n equal parts to the n+1 points on the edge on the opposite side of the square.at n=10A355839