131070

Appears in sequences

• a(n) = 2^n - 2.at n=17A000918
• a(n) = 2^(2*n+1) - 2.at n=8A002446
• a(n) = 2*a(n-1) if n odd else 2*a(n-1) + 6.at n=15A014131
• Number of aperiodic binary strings of length n; also number of binary sequences with primitive period n.at n=17A027375
• a(2*n) = 3*2^n - 2; a(2*n+1) = 2^(n+2) - 2.at n=31A027383
• Row sums of triangle T(m,n) = number of solutions to 1 <= a(1) < a(2) < ... < a(m) <= n, where gcd(a(1), a(2), ..., a(m), n) = 1, in A020921.at n=16A038199
• Number of 2n-bead balanced binary strings of fundamental period 2n, rotationally equivalent to complement.at n=17A045663
• Euler totient function (A000010) of 2^n - 1.at n=16A053287
• a(1) = 1; for n>1, sum of binomial(n,k) as k runs over RRS(n), the reduced residue system of n.at n=16A056188
• Number of primitive (aperiodic) words of length n which contain exactly two different symbols.at n=16A056267
• Number of palindromes of length n using exactly two different symbols.at n=32A056453
• Number of palindromes of length n using exactly two different symbols.at n=33A056453
• Largest solution of phi(x) = 2^n.at n=15A058215
• Least k such that the least factor of k^Phi(k) -1 is the n-th prime.at n=15A066732
• Biased numbers: n such that all terms of the sequence f(n), f(f(n)), f(f(f(n))), ..., 1, where f(k) = floor(k/2), are odd.at n=30A066880
• Numbers m such that phi(m) = tau(m)^3.at n=35A068559
• Integers n such that sigma(phi(n))/n = 1/2.at n=4A074777
• a(0) = 1; a(n) = a(n-1)+1 if n is even, otherwise a(n) = 2*a(n-1).at n=31A075427
• Largest term in periodic part of continued fraction expansion of square root of -1+2^n or 0 if -1+2^n is square.at n=31A077625
• Number of rational knots with n crossings and unknotting number = 1 (chiral pairs counted only once).at n=33A078477