1720320

Appears in sequences

• a(n) = binomial(n,2) * 2^(n-1).at n=15A001815
• Denominator of I(n)=integral_{x=0 to 1/n}(x^2-1)^3 dx.at n=3A094075
• Smallest number beginning with the digits of n that has exactly n prime factors (counted with multiplicity).at n=16A109686
• Denominators of expansion of exp(1-sqrt(1-x-x^2)).at n=8A144580
• Expansion x^2*cotan(x)/(exp(x^2*cotan(x))-1) = Sum_{n>=0} a(n)*x^n/(n+1)!^2.at n=7A199541
• Triangular array read by rows. T(n,k) is the number of cycles in the digraph representation of all functions f:{1,2,...,n}->{1,2,...,n} that have length k; 1<=k<=n.at n=31A225213
• Numbers k with the property that it is possible to write the base 2 expansion of k as concat(a_2,b_2), with a_2>0 and b_2>0 such that, converting a_2 and b_2 to base 10 as a and b, we have a' * b' = k, where a' and b' are the arithmetic derivatives of a and b.at n=31A259675
• Consider the Watanabe tag system defined in A291067; a(n) = number of binary words of length n which terminate at the empty word.at n=21A291780
• (1/8) times the sum of the elements of all subsets of [n] whose sum is divisible by eight.at n=20A309300
• Number of ways to choose a factorization of each integer from 2 to n into factors > 1.at n=23A321514
• Heinz numbers of integer partitions whose product of parts is one greater than their sum.at n=31A325041
• a(n) is the number of subsets of {1,2,...,n} that contain exactly two odd numbers.at n=28A330592
• Triangle read by rows: T(n, k) = binomial(n, k - 1) * (k - 1)^(k - 1) * (n - k) * (n - k + 1)^(n - k) / 2.at n=41A368982
• a(n) is the least k such that A161606(k) = n or a(n) = -1 if no such k exists.at n=17A385677
• Smallest integer k whose sum of its distinct prime factors and bigomega(k) both equal n; or -1 if no such integer exists.at n=15A386605
• The total number of big inversions in all parking functions of length n.at n=6A386861
• Smallest integer k with exactly n distinct prime factors such that the sum of those primes equals the sum of the exponents in its prime factorization.at n=3A390173