19399

Appears in sequences

• a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = a(3) = 1.at n=17A049885
• Number of step cyclic shifted sequences using exactly two different symbols.at n=21A056415
• Numbers k such that sigma(phi(sigma(k))) = sigma(k).at n=17A066471
• Number of (w,x,y,z) with all terms in {1,...,n} and |w-x|=w+|y-z|.at n=39A212685
• Number of partitions p of n such that (number of numbers in p of form 3k+2) > (number of numbers in p of form 3k).at n=41A241742
• Relative of Hofstadter Q-sequence: a(n) = max(0, n+19395) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.at n=5A283886
• Relative of Hofstadter Q-sequence: a(n) = max(0, n+19395) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.at n=38A283886
• Number of partitions of n with odd minimal and maximal parts.at n=40A325338
• a(n) = numerator of Sum_{1 <= i < j <= d(n)} 1/(d_j - d_i), sum over ordered pairs of divisors of n, where d(n) is the number of divisors of n.at n=21A330077