25839

Appears in sequences

• Ruth-Aaron numbers (1): sum of prime divisors of n = sum of prime divisors of n+1.at n=26A006145
• Number of partitions satisfying cn(0,5) + cn(1,5) + cn(4,5) <= cn(2,5) + cn(3,5).at n=43A039878
• Number of polyominoes with n cells, symmetric about two orthogonal axes.at n=34A056877
• The Wiener index of the Dutch windmill graph D(5,n) (n>=1).at n=32A180579
• Array read by rows: row n lists the coefficients of the characteristic polynomial of the n-th principal submatrix of max(2i-j, 2j-i), as in A204154.at n=28A204155
• Expansion of Product_{k>=1} (1 + 3*x^k)^k.at n=12A266857
• a(n) = [x^(n*(n+1)*(2*n+1)/6)] Product_{k=1..n} Sum_{m>=0} x^(k^2*m).at n=8A321186
• Numbers k such that both k and k+1 are not exponentially squarefree numbers.at n=18A342188
• Numbers k such that k and k+1 are products of at least 6 primes.at n=37A346207
• Number of polyominoes of n cells with both horizontal and vertical symmetries, for which the 180-degree rotational symmetry has an axis that coincides with the center of a square, but without 90-degree rotational symmetry.at n=34A351190
• Triangle read by rows: T(n,k) = n * T(n-1,k) + (-1)^(n-k) for 0 <= k <= n with initial values T(n,k) = 0 if n < 0 or k < 0 or k > n.at n=60A352650
• Smaller term of each Ruth-Aaron pair in which the sum of distinct prime factors is a prime number.at n=7A372455
• sqrt(a(n)) / 4 is the maximum area of any triangle with integer side lengths whose perimeter is n, or a(n) = -1 if there is no such triangle.at n=29A387833
• Smallest k for which a chain of linked rods of length 1, ..., k can be folded in half in exactly n dictinct ways.at n=30A390056