218880

Appears in sequences

• Denominator of mass (Sum 1/|Aut(H)|) of Hadamard matrices of order 4n.at n=4A048616
• Number of strongly triple-free subsets of {1, 2, ..., n}.at n=23A050295
• E.g.f. [1 -3x -sqrt(1-6x+x^2) -x*(1-x-sqrt(1-6x+x^2)) ]/2.at n=6A052736
• Number of zero trace primitive elements in Galois field GF(7^n).at n=7A192214
• T(n,k)=Number of nXk arrays containing k copies of 0..n-1 with every element equal to at least one diagonal or antidiagonal neighbor and the top left element equal to 0.at n=40A268142
• (1/3) times the sum of the elements of all subsets of [n] whose sum is divisible by three.at n=15A309295
• Numbers k such that sigma(sigma(k^4)) == 0 (mod k^2).at n=39A320425
• a(n) = ((p-1)^3 - (p-1)^2)/4 where p is the n-th prime.at n=24A331764
• a(n) = Product_{k=0..n} (L(k)+1), where L=A000032 (Lucas numbers).at n=6A374654