27209

Appears in sequences

• a(n) = (10n+1)*(10n+9).at n=16A001535
• a(n) = (2*n - 1)*(11*n^2 - 11*n + 6)/6.at n=19A063492
• a(1) = 1; set of digits of a(n)^2 is a subset of the set of digits of a(n+1)^2.at n=30A066825
• Greatest number m such that the fractional part of (Pi-2)^A153717(n) <= 1/m.at n=14A153721
• Principal diagonal of the convolution array A212891.at n=12A213436
• Number of permutations p of [n] such that 0p has a nonincreasing jump sequence beginning with four.at n=9A292170
• For any number n > 0, let f(n) be the function that associates k to the prime(k)-adic valuation of n (where prime(k) denotes the k-th prime); f establishes a bijection between the positive numbers and the arithmetic functions with nonnegative integer values and a finite number of nonzero values; let g be the inverse of f; a(n) = g(f(n) * f(n)) (where i * j denotes the Dirichlet convolution of i and j).at n=14A296857
• a(n) = Sum_{k=1..n} (-1)^(k+1) * floor(n/k)^3.at n=30A344721
• a(n) = 1*binomial(n,2) + 3*binomial(n,3) + 6*binomial(n,4) + 10*binomial(n,5).at n=14A361474
• Standard composition numbers of compositions whose maximal runs all belong to {(1), (2,2), (3,3,3), ...}.at n=28A389530