67404

Appears in sequences

• Sum of the 4th powers of the divisors of n is divisible by n.at n=14A046764
• Numbers m such that DivisorSigma(8*k-4, m) mod m = 0 holds presumably for all k; that is, (8*k-4)-power-sums of divisors of m are divisible by m for all k.at n=6A066291
• Numbers k such that 10^(2*k+1) - 10^k - 1 is prime.at n=8A183187
• k such that 10^(2*k+1)-j*10^k-1 is prime for some j = 1, 2, 4, 5, 7 or 8.at n=43A213881
• Numbers k such that R_k + 20 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=22A256722
• a(n) = sum of the perimeters of the Ferrers boards of the partitions of n. Also, sum of the perimeters of the diagrams of the regions of the set of partitions of n.at n=25A278355
• Triangle read by rows: T(n,k) = number of linear chord diagrams with n chords such that every chord has length at least k (1 <= k <= n).at n=41A293157