22110

Appears in sequences

• a(n) is the concatenation of n and 5n.at n=21A019553
• The recurrence b(k) = 10*b(k-1) + k^n with b(0)=0 has b(k)/10^k converging to a(n)/9^(n+1).at n=4A055530
• Ninth column of quintinomial coefficients.at n=8A064058
• A064637 converted to factorial base.at n=22A064477
• Numbers k such that Sum_{d divides k} sigma(d)/phi(d) is an integer.at n=26A068991
• Integers k such that omega(k) = omega(k-1) + omega(k-2) + omega(k-3), where omega(n) is the number of distinct prime factors of n.at n=14A076252
• The rightmost column of triangle A094280.at n=12A094282
• Smallest number m such that the trajectory of m under iteration of cototient function[=A051953] contains exactly n distinct numbers (including m and the fixed point=0). Or: the required number of iterations[=operations,transitions] is n-1.at n=24A098197
• Numbers n such that n divides the denominator of 2n-th Bernoulli number.at n=37A106741
• a(n+1) = a(n) + (if a(n) is odd then (next odd square) else (next even square)), a(0) = 1.at n=26A116955
• Averages of twin prime pairs of the form : sum of two or more consecutive squares.at n=18A174716
• Numbers of rank 11 in the poset of lunar numbers.at n=32A191753
• Triangle T(n,k), read by rows, of numbers T(n,k)=C^(4)(n,k) of combinations with repetitions from n different elements over k for each of them not more than four appearances allowed.at n=63A213743
• Numbers k with k - 1, k + 1, prime(k) - k, prime(k) + k, k*prime(k) - 1, k*prime(k) + 1 all prime.at n=0A232861
• Numbers m with m - 1, m + 1 and q(m) - 1 all prime, where q(.) is the strict partition function (A000009).at n=11A235346
• Practical numbers m with m-1 and m+1 both prime, and prime(m)-1 and prime(m)+1 both practical.at n=9A257922
• Number of nX6 0..1 arrays with every repeated value in every row greater than or equal to, and in every column greater than, the previous repeated value.at n=2A267786
• T(n,k)=Number of nXk 0..1 arrays with every repeated value in every row greater than or equal to, and in every column greater than, the previous repeated value.at n=30A267788
• Number of 3Xn 0..1 arrays with every repeated value in every row greater than or equal to, and in every column greater than, the previous repeated value.at n=5A267789
• Numbers k such that 1/phi(x) + 1/phi(y) = 1/phi(k), for some x + y = k and phi(k) is the Euler totient function of k.at n=24A279621