68607

Appears in sequences

• a(n) = (2*n - 3)n^2.at n=33A015238
• Odd numbers k that divide phi(k)*sigma(k).at n=30A015706
• Row sums of A075652.at n=32A075650
• Numbers k for which the quotient q(k)=(k+rev(k))/abs(k-rev(k)) is an integer.at n=27A087993
• a(n) = partitions(n)*partitions(n+1).at n=16A090982
• Triangle T(n,m) = (A006882(2*n + 1))^2 / ( A006882(2*m+1) * A006882(2*n-2*m+1) ).at n=17A153512
• Triangle T(n,m) = (A006882(2*n + 1))^2 / ( A006882(2*m+1) * A006882(2*n-2*m+1) ).at n=18A153512
• a(1) = 1, then partial products of Product_{n>=1} (p(n)/p(n-1)*p(n)/p(n-1)) = 1*1*1*(2)*(2)*(3/2)*(3/2)*(5/3)*(5/3)*(7/5)*(7/5)*...*; p = partition numbers, A000041 starting (1, 2, 3, 5, ...).at n=33A171646
• Pairs of primitive deficient numbers having the same value of sigma(k)/k, listed by increasing value of the larger of the two k values.at n=6A212610
• Primitive deficient numbers n having a companion m > n such that sigma(n)/n = sigma(m)/m (ordered by increasing (smallest possible) m).at n=3A212611
• E.g.f. A(x) satisfies: A(x) = exp( Integral A(x)^(1/2) * Integral 1/A(x)^(3/2) dx dx ).at n=6A258659
• Odd numbers of the form (m*k)^2/(m^2-k^2) for distinct integers m and k.at n=35A259288
• Unordered even-degree bilabeled increasing trees on 2n+1 nodes.at n=3A261000
• Numbers k with property that k is the least logarithmically smooth numbers (meaning largest prime factor of k is less than log(k)) having squarefree kernel equal to squarefree kernel of k.at n=27A333961
• Numbers k such that R(k)/k is of the form (m + 1)/m, where R(k) is the digital reversal of k.at n=12A376259
• a(n) is the conjectured largest number such that both a(n) and a(n) - n are 11-smooth numbers, or 0 if no such number exists. a(n) can be less than n.at n=6A392256