21702

Appears in sequences

• Numbers k such that x = 2^k-2 satisfies phi(x)+2 = phi(x+2).at n=24A050475
• a(n) = A088314(n) - A000009(n).at n=50A088571
• Triangle of coefficients of polynomials u(n,x) jointly generated with A209163; see the Formula section.at n=49A209162
• Numbers k such that prime(k) + 1, ..., prime(k + 5) + 1 have the same number of prime divisors (with multiplicity).at n=7A255193
• Number of length n arrays of permutations of 0..n-1 with each element moved by -3 to 3 places and with no two consecutive increases or two consecutive decreases.at n=15A263661
• a(1) = 1; thereafter a(n) = Sum_{k = 1..n} a(k/gcd(n,k)).at n=17A333613
• a(n) = [x^n] E(x)^n where E(x) = exp( Sum_{k >= 1} A000172(k)*x^k/k ).at n=5A362731