20905

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 55.at n=27A020394
• Fibonacci sequence beginning 0, 5.at n=19A022088
• Trajectory of 1 under map n->19n+1 if n odd, n->n/2 if n even.at n=33A033966
• Trajectory of 3 under map n->19n+1 if n odd, n->n/2 if n even.at n=24A037107
• Numbers whose base-12 representation has exactly 5 runs.at n=12A043654
• Sum of two consecutive squares of Lucas numbers (A001254).at n=9A106729
• Numerators of A178381(4*n+1)/A178381(4*n).at n=9A179131
• Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal, vertical or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and columns, 0..2 n X 2 array.at n=23A219293
• Rounded area of distinct right triangles appearing in the unit golden spiral.at n=20A221212
• Numbers whose septenary, octal and nonary representations are prime when read in decimal.at n=22A281252
• Numbers of the form p*q*r where p, q, r are distinct primes congruent to 1 mod 4 such that Legendre(p/q) = Legendre(p/r) = Legendre(q/r) = -1.at n=20A323271
• a(n) = Sum_{i=1..n, gcd(i,n)=1} i*phi(i) where phi is Euler's totient function A000010.at n=48A333291
• Square array read by upward antidiagonals: T(n, k) is the number of n-ary strings of length k containing 00.at n=42A340156
• Numbers that are the sum of seven fifth powers in two or more ways.at n=21A345605
• Numbers that are the sum of seven fifth powers in exactly two ways.at n=21A346279
• G.f. A(x) satisfies: A(x) = 1 / ((1 + x) * (1 - x * A(2*x))).at n=6A348860
• The number of quaternary strings of length n containing 00.at n=8A351529
• G.f. A(x) satisfies A(x) = 1 + x*A(x)^2 / (1 - x*A(x)^4).at n=7A364739
• Main diagonal of the extended Wythoff array (A287870).at n=15A367293
• E.g.f. A(x) satisfies A(x) = exp(x * A(x)^2 * (1 - x*A(x))) / (1 - x*A(x))^2.at n=4A380722