23728

Appears in sequences

• Numbers n such that 6*10^n + 5*R_n - 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=20A103038
• Number of ways the set {1,2,...,n} can be split into three subsets of equal sums.at n=17A112972
• G.f. of the z^1 coefficients of the FP1 in the second column of the A156921 matrix.at n=10A156928
• Numbers n such that sigma(sigma(phi(n))) = sigma(sigma(n)).at n=31A172466
• Number of arrangements of 4 nonzero numbers x(i) in -n..n with the sum of div(x(i),x(i+1)), where div(a,b)=a/b produces the integer quotient implying a nonnegative remainder, equal to zero.at n=10A190073
• Irregular triangle read by rows where T(n,k) is the number of set partitions of {1,...,n} with all block-sums equal to d, where d is the k-th divisor of n*(n+1)/2 that is >= n.at n=51A320438