18288

Appears in sequences

• a(n) is the number of permutations w of 1,2,...,n such that both w and w^{-1} are alternating.at n=12A007999
• Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (3,k)-perfect numbers.at n=20A019292
• Numbers k such that sigma (x) = k has exactly 11 solutions.at n=21A060678
• Least multiple k of prime(n) such that (k-1,k+1) forms a twin prime pair, or 0 if no such number exists.at n=30A090530
• Average of twin prime pairs with multiple and strictly distinct powers.at n=24A177426
• Number of nX4 binary arrays with each element equal to either the sum mod 2 of its horizontal and vertical neighbors or the sum mod 2 of its diagonal and antidiagonal neighbors.at n=5A183512
• Number of nX6 binary arrays with each element equal to either the sum mod 2 of its horizontal and vertical neighbors or the sum mod 2 of its diagonal and antidiagonal neighbors.at n=3A183514
• T(n,k)=Number of nXk binary arrays with each element equal to either the sum mod 2 of its horizontal and vertical neighbors or the sum mod 2 of its diagonal and antidiagonal neighbors.at n=39A183517
• T(n,k)=Number of nXk binary arrays with each element equal to either the sum mod 2 of its horizontal and vertical neighbors or the sum mod 2 of its diagonal and antidiagonal neighbors.at n=41A183517
• Number of nXnXn 0..6 triangular arrays with each element x equal to the number its neighbors equal to 5,0,2,1,1,1,2 for x=0,1,2,3,4,5,6.at n=5A198091
• Product between n-th prime and next perfect square.at n=30A229497
• Partial sums of the Jordan function J_2(k), for 1 <= k <= n.at n=40A321879
• A(n, k) = Stirling2(n + k, k)*A053657(n)*k!/(n + k)!, array read by ascending antidiagonals for n >= 0 and k >= 0.at n=38A325146
• Triangular array read by rows: row n shows the coefficients of this polynomial of degree n: p(x,n) = 2^(n-1) ((x+r)^n - (x+s)^n)/(r - s), where r = 1 and s = 1/2.at n=38A327318
• a(n) is the number of partitions of n with Durfee square of size <= 3.at n=40A330641
• a(n) = r_4(n^2 + 1), where r_4(k) is the number of ways of writing k as a sum of 4 squares (A000118).at n=39A333173