22019

Appears in sequences

• Increasing gaps between squarefree numbers (lower end).at n=6A020754
• Positive integers of the form (18*m^2+1)/11.at n=21A113338
• a(1)=0, a(n+1) is smallest nonprime > 2*a(n).at n=14A156321
• Number of 9-element subsets of {1, 2, ..., n} having pairwise coprime elements.at n=18A186985
• a(n) = prime(n) * prime(2*n-1).at n=24A219603
• Number of length 3 1..(n+1) arrays with every leading partial sum divisible by 2, 3, 5, 7 or 11.at n=34A254950
• T(i, j) = k is the least squarefree number with a run of exactly i>=0 nonsquarefree numbers immediately preceding k and a run of exactly j>=0 nonsquarefree numbers immediately succeeding k.at n=27A270996
• a(n) = k is the least squarefree number with a run of zero nonsquarefree numbers immediately preceding k and a run of exactly n>=0 nonsquarefree numbers immediately succeeding k.at n=6A271041
• Number of integer partitions of n whose second differences sum to 0, meaning either there is only one part, or the first two parts have the same difference as the last two parts.at n=48A360683
• a(n) is the smallest k such that the sum of the first k primes has exactly n prime factors, counting multiplicity.at n=14A385997