19693

Appears in sequences

• Sum of 11 positive 9th powers.at n=12A004800
• Numbers n such that sigma(phi(n))/sigma(n) = 2.at n=32A067382
• a(n) = Sum_{k=1..n} k^(n-k)*binomial(n-1,k-1).at n=7A080108
• Euler-Seidel matrix T(k,n) with start sequence A000248, read by antidiagonals.at n=28A098697
• a(1) = 1; for n>1, a(n) = least k such that concatenation of n copies of k with all previous concatenations gives a prime.at n=34A111471
• Rectangular array of coefficients in successive iterations of x*exp(x), as read by antidiagonals.at n=43A174480
• Members of a pair (m,n) such that sigma(m) = sigma(n) = sigma(n-m), m < n where sigma = A000203.at n=9A239939
• Members of a pair (m,n) such that sigma(m) = sigma(n) = sigma(n-m), m < n where sigma = A000203.at n=11A239939
• Number of distinct positive integers that can be obtained by iteratively adding any two or multiplying any two non-1 parts of an integer partition until only one part remains, starting with 1^n.at n=30A319909
• a(n) = Sum_{d|n} d^(n-d) * (n/d)^d.at n=8A359883
• Numbers k such that k, k+1, k+2, k+3 have 2, 3, 4, 5 prime factors respectively, counted with multiplicity.at n=22A363391
• Squarefree semiprimes k such that k+1 is the product of three distinct primes and k+2 is the product of four distinct primes.at n=20A376352