35640

Appears in sequences

• Numbers k such that the set of prime divisors of k is equal to the set of prime divisors of sigma(k).at n=19A027598
• Expansion of (eta(q) * eta(q^9))^12 in powers of q.at n=25A034436
• Numbers expressible as (a^2-1)(b^2-1) in at least 2 distinct ways (b>=a>1).at n=23A063067
• Numbers n such that sigma(n) is congruent to n mod phi(n).at n=17A066679
• Smallest solution to x+n*phi(x) = sigma(x) = x+n*A000010(x) = A000203(x).at n=10A076374
• Second binomial transform of binomial(n+3, 3).at n=7A081895
• Numbers k such that sigma(k) divides k^2.at n=27A090777
• Triangle read by rows: T(n,k) is the number of permutations p of [n] in which the length of the longest initial segment avoiding the 123-pattern is equal to k.at n=41A092583
• Triangle read by rows: T(n,k) is the number of ternary trees with n edges and such that the first leaf in the preorder traversal is at level k (1<=k<=n). A ternary tree is a rooted tree in which each vertex has at most three children and each child of a vertex is designated as its left or middle or right child.at n=32A121445
• Expansion of a(q)^2 * (b(q) * c(q) / 3)^3 in powers of q where a(), b(), c() are cubic AGM theta functions.at n=23A136747
• Lower triangular array called S1hat(3) related to partition number array A144880.at n=29A144881
• Second column (m=2) of triangle A144881 (S1hat(3)).at n=6A144883
• Numbers n for which sigma(n)/n=k+2/3 with integer k.at n=5A160321
• a(n) = binomial(n+8,8)*6^n.at n=3A172501
• Numbers with prime factorization pqr^3s^4.at n=5A190294
• Places n such that the two remainders A187680(n) and A191906(n) are both zero.at n=21A192853
• Smallest number m such that the numerator of sigma(m)/m is equal to n, or zero if no such m exists.at n=10A239578
• Numbers n with the property that it is possible to write the base 2 expansion of n as concat(a_2,b_2), with a_2>0 and b_2>0 such that, converting a_2 and b_2 to base 10 as a and b, we have sigma(a)*sigma(b) = n.at n=19A244079
• Numbers k that divide 3*sigma(k).at n=20A245774
• Numbers k such that A017666(k) = denominator(sigma(k)/k) = 3.at n=11A245775