388080

Appears in sequences

• Numbers k such that 2*k+1 and 3*k+1 are squares.at n=3A045502
• Even legs of Pythagorean triangles whose other leg and hypotenuse are both prime.at n=29A067755
• Least common multiple of all cycle sizes in range [A014137(n-1)..A014138(n-1)] of permutation A071663/A071664.at n=9A089871
• Highly abundant numbers (A002093) that are not Harshad numbers (A005349).at n=6A128702
• a(n) = numerator of Product_{k=1..n} k^mu(k), where mu(k) = A008683(k).at n=34A130086
• a(n) = numerator of Product_{k=1..n} k^mu(k), where mu(k) = A008683(k).at n=35A130086
• a(n) = numerator of Product_{k=1..n} k^mu(k), where mu(k) = A008683(k).at n=36A130086
• a(n) = 2*n*a(n-1) if the parity of the ratio a(n-1)/a(n-2) is odd, otherwise (for even parity) a(n) = (2n-1)*a(n-1).at n=7A177373
• a(n) = sigma(n)*Pell(n), where sigma(n) = A000203(n), the sum of divisors of n.at n=11A204271
• Triangle read by rows, T(n,k) (n>=0, 0<=k<=n) coefficients of the partial fraction decomposition of rational functions generating the columns of A247495 (the Motzkin polynomials evaluated at nonnegative integers).at n=41A247497
• Numbers k such that floor(Sum_{d|k} 1 / sigma(d)) = 3.at n=7A265713
• Highly composite numbers of class 2 (see comment in A275239).at n=35A275240
• Index of first occurrence of n in the Erdös-Hooley Delta function A226898, with a(0)=0.at n=30A309278
• Numbers k achieving record abundance (sigma(k) > 2*k) via a residue-based measure M(k) (see Comments), analogous to superabundant numbers A004394.at n=24A362081
• Number of partitions of [n] whose blocks are ordered with increasing least elements and where block i (except possibly the last) has size i.at n=16A362639
• a(n) = lcm({1, 2, ..., n}) * (n + 1) / n for n > 0, a(0) = 1.at n=13A387027
• Square array A(n,k) = A388979(A388981(n, k)), read by descending antidiagonals.at n=13A389169