73152

Appears in sequences

• Number of ways to choose n positive integers less than or equal to 2n such that none of the n integers divides another.at n=39A174094
• The number of sets of n positive integers strictly less than 2*n such that no integer in the set divides another.at n=39A192298
• Numbers k for which sigma(k)/k - 8/9 is an integer.at n=2A218418
• Numbers n with the property that it is possible to write the base 2 expansion of n 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 sigma(a)*sigma(b) = n.at n=21A244079
• a(n) = n! * [x^n] exp(n*sinh(x)).at n=6A293022
• Numbers m that divide sigma(sigma(m) - m) where sigma is the sum of divisors function (A000203).at n=25A300658
• Totients t such that the number of divisors of t equals the number of solutions of phi(x) = t.at n=33A305058
• Numbers which can written in exactly four ways as a sum of two distinct nonzero pentagonal numbers.at n=8A333014
• a(n) = Sum_{k=0..n} (k+1) * 2^k * binomial(2*k,2*(n-k)).at n=7A390700