22848

Appears in sequences

• Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (3,k)-perfect numbers.at n=21A019292
• "DHK[ 6 ]" (bracelet, identity, unlabeled, 6 parts) transform of 1,1,1,1,...at n=26A032247
• (Terms in A029665)/2.at n=55A051425
• (Terms in A029643)/2.at n=54A051469
• a(n) = A028321(n)/2.at n=35A051473
• Let f(x) = phi(x) + sigma(x); a(n) = least k such that at k begins a maximal run of length n of consecutive strict local extrema of f, or 0 if no such k exists.at n=19A066923
• a(n) = Product_{i=2..n} A001222(i) * Sum_{i=2..n} 1/A001222(i).at n=14A067580
• Smallest number k for which the set of solutions to phi(x) = k has 2n-1 entries.at n=33A071387
• Least number m such that cardinality of InvPhi(m) = prime(n).at n=18A071389
• Numbers k such that d(phi(k)) = phi(d(k)), where d=A000005 and phi=A000010.at n=35A078148
• Numbers that can be expressed as the difference of the squares of primes in exactly five distinct ways.at n=25A092001
• Records in A007374.at n=17A105207
• a(n) = (n+1)*(n+2)^3*(n+3)*(2n+3)*(2n+5)/360.at n=6A107970
• Triangle read by rows: T(i,j) = F(i)*F(j)*C(i,j) for 1 <= j <= i, where F(n) is the n-th Fibonacci number and C(n,m) is a binomial coefficient.at n=41A117965
• a(n) = n*(n+2)*(2*n-1)/3. Also, row sums of triangle A131422.at n=31A131423
• Duplicate of A131423.at n=31A143371
• G.f. A(x) satisfies: A(x) = 1+x + x^2*A(x)*A'(x).at n=8A143916
• Triangle T(n,k) read by rows: coefficient [x^k] of the polynomial Product_{i=1..n} (x + q^i) in row n, column 0<=k<=n, and q = 4.at n=12A173008
• Ordered (2,2)-selections from the multiset {1,1,2,2,3,3,...,n,n}.at n=17A188667
• Bi-unitary multiperfect numbers.at n=8A189000