31801

Appears in sequences

• Numbers n such that 219*2^n-1 is prime.at n=13A050861
• a(n) = A083960(n)/A004151(n).at n=28A083961
• Numbers n such that (n + prime(n)), (n+1 + prime(n+1)), (n+2 + prime(n+2)) and (n+3 + prime(n+3)) are divisible by 5.at n=19A107582
• Numbers k such that k and k^2 use only the digits 0, 1, 3, 6 and 8.at n=14A136849
• Number of crossings in a regular drawing of the complete bipartite graph K(n,n).at n=22A159065
• G.f.: (1+x+x^3+x^5)/( (1-x^2+x^3)*(1-x-x^3) ).at n=26A177485
• Number of parts in all partitions of n in which no part occurs more than twice.at n=39A185350
• For any number n with runs in binary expansion (r_w, ..., r_0), let p(n) be the polynomial of a single indeterminate x where the coefficient of x^e is r_e for e = 0..w and otherwise 0, and let q be the inverse of p; a(n) = q(p(n)').at n=42A355653
• a(n) is the integer whose binary expansion starts with 1 and such that the runs of identical bits have lengths n, n-1, n-2, ..., 3, 2, 1.at n=4A371033