19924

Appears in sequences

• Number of squarefree integers in closed interval [2^n, -1 + 2*2^n], i.e., among 2^n consecutive numbers beginning with 2^n.at n=15A077643
• Monotonically increasing sequence of least positive integers, a(1)=1, such that the self-convolution produces all squares.at n=25A087150
• a(n) = Sum_{k=1..n} k*lcm(k,k')/gcd(k,k'), where k' is arithmetic derivative of k.at n=23A190122
• Numbers n such that 4n+1 is a palindromic prime.at n=43A192261
• a(1) = 1; a(2) = 1; for n >= 3, a(n) = a(n-1) / gcd(a(n-1), n-1) + a(n-2) / gcd(a(n-2), n-2).at n=37A330806
• a(n) = (8*n^3 + 15*n^2 + 13*n)/6.at n=24A332698
• Number of n-step self-avoiding walks on one quadrant of a 2D square lattice where the walk cannot step to the smaller square ring of numbers than the ring it is currently on.at n=12A348009