19866

Appears in sequences

• G.f.: 2*(1-x^3)/((1-x)^5*(1+x)^2).at n=41A005996
• a(n) = floor(n*(n-1)*(n-2)/4).at n=44A011886
• Number of 5-tuples of different integers from [ 2,n ] with no global factor.at n=20A015641
• Composite numbers divisible by the palindromic sum of their prime factors (counted with multiplicity).at n=32A046358
• Smallest area of a Pythagorean triangle with n as length of one of the three sides.at n=40A054435
• Smallest area of a Pythagorean triangle with n as length of a leg.at n=40A054436
• a(n) = n*(n+1)*(2*n+1).at n=21A055112
• Largest area of a Pythagorean triangle with n as length of one of the three sides (in fact as a leg).at n=40A055522
• a(n) = rad(n(n+1)(n+2)), where rad(m) is the largest squarefree number dividing m (see A007947).at n=41A078637
• Values of z arising from representations of -n in A102535.at n=22A102809
• Composite numbers that are products of distinct primes and divisible by the sum of those primes.at n=40A131647
• a(n) = largest value of the function rad(m*n*(n - m)) n=2,3,4,..., 0 < m < n where the function rad(k) (also called radical(k)) is the product of distinct prime divisors of k.at n=41A147299
• Squarefree positive integers of the form u*v*(u^2-v^2) for some integer u,v.at n=19A147779
• Row sums of A163233 and A163235 divided by 3.at n=42A163478
• a(n) = 11*n*(n+1).at n=42A164136
• Numbers k with the property that k^2 is a product of two distinct triangular numbers.at n=37A175497
• Number of -n..n arrays x(0..3) of 4 elements with zero sum, adjacent elements differing by more than one, and elements alternately increasing and decreasing.at n=20A200193
• Number of n X n 0..4 matrices with each 2X2 subblock idempotent.at n=10A224661
• Number n such that the sum of its proper evil divisors (A001969) equals n.at n=27A230587
• Smallest integer areas of integer-sided triangles such that the perimeter equals n times the smallest side.at n=43A237576