87381

Appears in sequences

• a(2n) = 2*a(2n-1), a(2n+1) = 2*a(2n)+1 (also a(n) is the n-th number without consecutive equal binary digits).at n=17A000975
• Jacobsthal sequence (or Jacobsthal numbers): a(n) = a(n-1) + 2*a(n-2), with a(0) = 0, a(1) = 1; also a(n) = nearest integer to 2^n/3.at n=18A001045
• a(n) = (4^n - 1)/3.at n=9A002450
• Divisors of 2^18 - 1.at n=30A003528
• Expansion of bracket function.at n=14A006090
• Indices of last windows of trapezoidal maps.at n=17A007873
• Smallest start for a '3x+1' sequence containing 2^n.at n=17A010120
• Smallest start for a '3x+1' sequence containing 2^n.at n=18A010120
• Number of Barlow packings with group P3(bar)m1(SO) that repeat after 2n-1 layers.at n=18A011950
• Gaussian binomial coefficients [ n,8 ] for q = 4.at n=1A022207
• a(n) = C(n,1) + C(n,4) + ... + C(n, 3*floor(n/3) + 1).at n=17A024494
• a(n) = C(n,2) + C(n,5) + ... + C(n, 3*floor(n/3)+2).at n=18A024495
• a(n) = Sum_{k=0..floor(n/2)} A026637(n, k).at n=17A026645
• a(n) = binomial(n+4,4)*(4*n+5)/5.at n=17A034263
• Triangle read by rows: T(n,k) = T(n-1,k-1) + k^2*T(n-1,k), 1 < k <= n, T(n,1) = 1.at n=46A036969
• G.f.: 1/((1-x)*(1-x^2))^3.at n=34A038163
• Numbers n such that number of runs in the base 4 representation of n is congruent to 1 mod 9.at n=24A043859
• Numbers n such that number of runs in the base 4 representation of n is congruent to 1 mod 10.at n=24A043868
• Numbers that are repdigits in base 4.at n=25A048329
• Expansion of 1/((1 - x)*(1 - 2*x)*(1 + 2*x)).at n=16A052992