39420

Appears in sequences

• Triangle read by rows: number of permutations of 1..n by length of longest run.at n=40A010026
• Denominators of continued fraction convergents to sqrt(731).at n=3A042407
• Sums of squares of primitive roots of primes.at n=19A089453
• a(n) = 4*n*(floor(n^2/2)+1). For n >= 3, this is the number of directed Hamiltonian paths on the n-prism graph.at n=27A124350
• Indices of primes of the form 2^t*3^u + 1 in the primes.at n=36A174099
• Triangle read by rows: number of permutations of 1..n by length l of longest run (n >= 1, 1 <= l <= n).at n=50A211318
• Number of permutations of order n with the length of longest run equal 6.at n=4A230129
• Exponential (2,4)-perfect numbers: numbers m such that esigma(esigma(m)) = 4m, where esigma(m) is the sum of exponential divisors of m (A051377).at n=18A328133
• Triangle read by rows: T(n,k) is the number of permutations of {1,...,n} whose longest embedded arithmetic progression has length k.at n=50A339941