55385

Appears in sequences

• Indices of triangular numbers which are also pentagonal.at n=5A046175
• a(n) = 5*a(n-1) - 5*a(n-2) + a(n-3) with a(1) = 1 and a(k) = 0 if k <= 0.at n=9A061278
• a(n) = (2*n+1)*(2*n+3)*(2*n+5)/3.at n=26A162540
• Numbers n such that n and n+-1 have 4 distinct prime factors.at n=6A168628
• a(1) = least k such that 1/2+1/3+1/4+1/5 < H(k) - H(5); a(2) = least k such that H(a(1)) - H(5) < H(k) -H(a(1)), and for n > 2, a(n) = least k such that H(a(n-1)) - H(a(n-2)) > H(k) - H(a(n-1)), where H = harmonic number.at n=6A228025
• The number of 3-length segments in all possible covers of L-length line by these segments with allowed gaps < 3.at n=33A228494
• Numbers k such that phi(k) = phi(k+2) - phi(k+1).at n=25A229552
• a(n) = Sum_{k=0..floor(n/2)} 2^(n-2*k) * binomial(2*n-2*k+1,2*k+1).at n=8A387694