20471

Appears in sequences

• Related to population of numbers of form x^2 + y^2.at n=16A000693
• Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 13.at n=10A031691
• Floor(X/Y) where X = concatenation of the (n+1)-st even number through the (2n)-th even number and Y = concatenation of first n even numbers.at n=23A067091
• a(n) = 10*2^(n-1) - 9.at n=11A139634
• a(n) = 169*n^2 + 2*n.at n=10A158220
• G.f.: exp( Sum_{n>=1} A174466(n)*x^n/n ) where A174466(n) = Sum_{d|n} d*sigma(n/d)*tau(d).at n=16A174465
• a(n) = n + (n-1)*(2^n-2).at n=11A188716
• Number of distinct values of Sum_{i=0..n} x(i)*binomial(n,i), where the x(i) have values in 0..5.at n=12A205540
• Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and columns, 0..2 n X 2 array.at n=21A219621
• a(n) is the least number that can be written in exactly n ways as p*q + q*r + p*r where (p,q,r) is an unordered triple of distinct primes.at n=30A356457
• G.f. A(x) satisfies A(x)^3 = A(x^3) / (1 - 3*x)^3 with A(0)=1.at n=9A372870