21621600

Appears in sequences

• Superior highly composite numbers: positive integers n for which there is an e > 0 such that d(n)/n^e >= d(k)/k^e for all k > 1, where the function d(n) counts the divisors of n (A000005).at n=12A002201
• Superabundant [or super-abundant] numbers: n such that sigma(n)/n > sigma(m)/m for all m < n, sigma(n) being A000203(n), the sum of the divisors of n.at n=38A004394
• Colossally abundant numbers: m for which there is a positive exponent epsilon such that sigma(m)/m^{1 + epsilon} >= sigma(k)/k^{1 + epsilon} for all k > 1, so that m attains the maximum value of sigma(m)/m^{1 + epsilon}.at n=12A004490
• a(1)=1; for n > 1, a(n) is the smallest number with the same number of divisors as 2*a(n-1).at n=28A019505
• Least common multiple of the first n composite numbers.at n=20A025543
• Least common multiple of the first n composite numbers.at n=21A025543
• Triangle read by rows. A generalization of unsigned Lah numbers, called L[4,1].at n=40A048854
• Number of labeled groups with a fixed identity.at n=11A058163
• Smallest number with exactly n^2 divisors.at n=23A061707
• Distinct values arising in the sequence of the least common multiples of the first n composite numbers.at n=12A064354
• Number of permutations of {1,2,3,...,n} where the elements of n are considered indistinguishable if they differ by a power of 2 (for example 3, 12 and 24 are all considered equivalent).at n=13A067281
• Least k such that n*prime(k) <= k*tau(k).at n=28A073066
• Least k such that n*prime(k) <= k*tau(k).at n=27A073066
• Least k such that n*prime(k) <= k*tau(k).at n=29A073066
• LCM of the composite numbers between n and 2n (both inclusive).at n=15A073841
• Square roots of squares pertaining to A076123.at n=10A076124
• Numbers k such that sigma(k)/k >= sigma(m)/m for all m <= k.at n=39A077006
• "Second order" highly composite numbers: the gap between the number of divisors (d(n)) rises to a new record.at n=8A095717
• Minimal numbers having in canonical prime factorization at least one factor p^e such that e+1 is not prime, p prime and e>0.at n=31A099317
• a(1) = 1. For n >= 2, a(n) = sum of the two (not necessarily distinct) earlier terms, a(j) and a(k), which maximizes d(a(j)+a(k)), where d(m) is the number of positive divisors of m. a(n) = the minimum (a(j)+a(k)) if more than one such sum has the maximum number of divisors.at n=31A115387