78705

Appears in sequences

• a(n) = n*(2*n-1)*(2*n+1).at n=27A035328
• Erroneous version of A057981.at n=2A060767
• a(0)=1, a(n) = (3n-1)*3n*(3n+1)/2 for n>0.at n=18A157024
• Denominator of a-sequence for Sheffer triangle A060081.at n=52A176727
• Triangle read by rows: T(n,k) is the number of up-down permutations of {1,2,...,n} having genus k (see first comment for definition of genus).at n=59A178516
• Nodes of tree generated as follows: (1,2) is an edge, and if (x,y) is an edge, then (y, y^2 - x^2) and (y, y^2 + x^2) are edges.at n=25A228940
• Members of a pair (m,k) such that sigma(m) = sigma(k) = sigma(m+k), m < k where sigma = A000203.at n=33A239436
• Number of (n+1) X (3+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.at n=23A250724
• From higher-order Bernoulli numbers: denominator of D Number D2n(2n).at n=26A261274
• a(n) is the maximum value of the quartet index of a bifurcating rooted tree with n leaves.at n=46A300445
• Associated Omega numbers of order 3, triangle T(n,k) read by rows for n >= 0 and 0 <= k <= n.at n=13A318255
• Smallest fixed points (>0) of the base-2*n Kaprekar map.at n=26A319839