25160

Appears in sequences

• Numbers k such that k*Sum_{d|k} 1/sigma(d) is an integer.at n=21A069166
• a(n) = 2^phi(n) - Sum_{j=0..n} binomial(phi(n), phi(j)).at n=18A073318
• A version of F. K. Hwang's sequence in {3*k, 3*k+1, 3*k+2}.at n=42A123945
• a(3n) = floor(43*2^n/28) - 1, a(3n+1) = a(3n) + 3*2^(n-3), a(3n+2) = floor(17*2^n/7 - 6/7) for n>=3.at n=42A123946
• Sum_(x^i*y^j*z^k) with i + j + k = m and (x, y, z) = the primitive Pythagorean triple (8, 15, 17).at n=3A124100
• G.f. satisfies: A(x) = 1 + x*A(x+x^2)^2.at n=8A127783
• a(n) = 441*n^2 - 394*n + 88.at n=7A157734
• Number of permutations p of {1,...,n} satisfying p(1)=1 and, if n>1, |p(i)-p((i mod n)+1)| is in {2,3} for i from 1 to n.at n=45A174469
• Irregular triangle read by rows: T(n,k) = number of unsigned unichromosonal genomes with n genes at 4-break distance k from a fixed genome, 0 <= k <= floor((n+1)/3).at n=23A264616
• a(1) = 15; for n > 1, a(n)^2 is the smallest square that begins with a(n-1) in base 6.at n=32A336251