20896

Appears in sequences

• Number of divisor chains of length n which begin with n ("anchored" divisor chains).at n=26A094097
• Number of divisor chains of length 2n+1 which are both cyclic and anchored.at n=13A094099
• a(n) = phi(Padovan(n+4)).at n=39A107797
• The number of homogeneous trisubstituted linear alkanes.at n=31A159938
• Number of 2 X 2 matrices having all terms in {1,...,n} and nonnegative even determinant.at n=15A211066
• Number of (n+1)X(3+1) 0..2 arrays with no element equal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.at n=1A231415
• T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with no element equal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.at n=7A231419
• Number of (2+1)X(n+1) 0..2 arrays with no element equal to a strict majority of its horizontal, diagonal and antidiagonal neighbors, with values 0..2 introduced in row major order.at n=2A231421
• Smallest number that is the largest value in the Collatz (3x + 1) trajectories of exactly n initial values. (a(n)=0 if no such number exists.)at n=37A233293
• Numbers n such that (n^n-2)/(n-2) is an integer.at n=27A242787
• Numbers k such that (151*10^k - 7)/9 is prime.at n=19A289535
• a(n) is the number of integer partitions of n for which the rank is equal to the index of the seaweed algebra formed by the integer partition paired with its weight.at n=57A318205
• Triangle read by rows: T(n,m) (n >= m >= 1) = number of regions (or cells) formed by drawing the line segments connecting any two of the 2*(m+n) perimeter points of an m X n grid of squares.at n=50A331452
• Irregular table read by rows: Take a triangle with Pythagorean triple leg lengths with all diagonals drawn, as in A332978. Then T(n,k) = number of k-sided polygons in that figure for k >= 3 where the legs are divided into unit length parts.at n=26A333135
• a(n) is the n-th nonnegative number to light exactly n segments when displayed on a calculator.at n=25A339700
• Irregular triangle read by rows: T(n,k) is the coefficient of x^k in the domination polynomial of the n X n grid graph (n>=1, A104519(n+2)<=k<=n^2).at n=44A378412