19788

Appears in sequences

• Numbers k such that phi(k)*sigma(k) is a cube.at n=10A114077
• Let f(z) = z^2 + c, then row k lists the expansion of the n-fold composition f(f(...f(0)...)) in rising powers of c.at n=62A137560
• Molecular topological indices of the cycle graphs.at n=33A192797
• Triangle by rows, related to the numbers of binary trees of height less than n, derived from the Mandelbrot set.at n=38A202019
• 1/4 the number of n X n 0..3 symmetric matrices with every element equal to one or two horizontal and vertical neighbors.at n=4A211080
• Number of (n+2) X (7+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 1 and no antidiagonal sum 2 and no row sum 0 and no column sum 3.at n=39A255800
• Triangle, read by rows, T(n,k) = k*Sum_{i=0..(n-k)/2} C(k,i)*C(2*n-k-4*i-1,n-2*i-k)/(n-2*i).at n=56A257558
• Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000001 00000101 or 00001011.at n=9A261548
• T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00000101 or 00001011.at n=45A261553
• Number of nXnXn triangular 0..6 arrays with new values introduced in sequential zero-upwards order and exactly one upright 2x2x2 triangle having values all equal.at n=3A271338
• T(n,k)=Number of nXnXn triangular 0..k arrays with new values introduced in sequential zero-upwards order and exactly one upright 2x2x2 triangle having values all equal.at n=39A271339
• G.f. A(x) satisfies: A( 4*A(x)^2 - 16*A(x)^3 ) = 4*x^2.at n=6A271961
• a(n) = 4*n*(n^2 + 2).at n=16A292022
• a(n) = (2*n-3-(-1)^n)*(22*n^2-21*n+5*n*(-1)^n)/96.at n=35A298992
• Number of (binary) max-heaps on n elements from the set {0,1} containing exactly seven 0's.at n=24A326508
• Number of binary search trees (BST) on n nodes which have the same height as the optimal BST.at n=24A328349
• Numbers k such that s(k) = s(k+1), where s(k) is the unitary analog of the alternating sum-of-divisors function (A307037).at n=12A333408
• Number T(n,k) of binary search trees of height k having n internal nodes; triangle T(n,k), k>=0, k<=n<=2^k-1, read by columns.at n=40A335920