27936

Appears in sequences

• arctan(arctan(x)*log(x+1))=2/2!*x^2-3/3!*x^3-10/5!*x^5-32/6!*x^6...at n=9A012399
• E.g.f. tanh(arctan(x)*log(x+1)).at n=7A012403
• Least term in period of continued fraction for sqrt(n) is 7.at n=34A031431
• a(n) = Sum_{k=1..n, gcd(n,k) = 1} k^3.at n=23A053819
• Numbers k such that sigma (x) = k has exactly 11 solutions.at n=33A060678
• Product of sums of divisors and non-divisors.at n=34A066859
• Numbers occurring twice in A068627.at n=24A068628
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, 0, 0), (-1, 1, 1), (1, 0, 0), (1, 0, 1)}.at n=8A150667
• Number of matrices with elements 1..n in which every pair of adjacent elements are relatively prime.at n=8A168078
• Numbers such that the largest prime factor equals the sum of the 4th power of the other prime factors.at n=17A244344
• Irrational parts of circle radii in nested circles and hexagons (see comment).at n=5A255163
• Expansion of 1/(1 - Sum_{k>=2} floor(bigomega(k)/2)*floor(2/bigomega(k))*x^k), where bigomega(k) is the number of prime divisors of k counted with multiplicity (A001222).at n=54A280238
• a(n) = Sum_{1 <= j <= n/2, gcd(j,n)=1} j^3.at n=47A295575
• Number of excursions of length n with Motzkin-steps avoiding the consecutive steps UU, HH, HD and DH.at n=26A329692
• a(n) = Fibonacci(n+1)^4 - Fibonacci(n-1)^4.at n=6A358917
• Expansion of (1/x) * Series_Reversion( x * (1-x-x^3/(1-x)^2) ).at n=9A367413
• Table read by downward antidiagonals: T(n,k) is the number of tilings of the n X k torus up to horizontal reflections by two tiles that are both fixed under horizontal reflection.at n=31A368305
• Number of subsets of {1..n} where no two elements sum to a prime.at n=27A391562