67054

Appears in sequences

• Number of 5k+3 primes (A030431) in range ]2^n,2^(n+1)].at n=21A095023
• Triangle read by rows: T(n,k) is the number of permutations of [n] having k-1 alternating descents (1<=k<=n). The index i is an alternating descent of a permutation p if either i is odd and p(i)>p(i+1), or i is even and p(i)<p(i+1).at n=39A145876
• Triangle read by rows: T(n,k) is the number of permutations of [n] having k-1 alternating descents (1<=k<=n). The index i is an alternating descent of a permutation p if either i is odd and p(i)>p(i+1), or i is even and p(i)<p(i+1).at n=41A145876
• Numbers k that divide A239868(k).at n=14A239869
• Expansion of b(3)*b(4)/(1 - 2*x + x^2 - x^3 + x^4), where b(k) = (1-x^k)/(1-x).at n=23A266353
• Consider a number x > 1. Take the sum of its digits. Repeat the process deleting the first addendum and adding the previous sum. The sequence lists the numbers that after some iterations reach the Euler totient function of x.at n=23A269310
• Number of permutations of [n] having exactly three alternating descents.at n=5A302896
• Number of permutations of [n] having exactly five alternating descents.at n=3A302898