27025

Appears in sequences

• Number of ways to place zero or more nonadjacent 0,0 1,0 2,1 3,2 4,3 5,3 polyhexes in any orientation on a planar nXnXn triangular grid.at n=7A155312
• First of two complementary trees generated by the triangular numbers. The second tree is A183232.at n=32A183231
• a(n) = a(n-1) + 2*a(n-2) - a(n-3) - a(n-4) + 2*a(n-5) - 2*a(n-7) for n>7 and where a(0)=2, a(1)=3, a(2)=6, a(3)=10, a(4)=17, a(5)=29, a(6)=51.at n=17A285665
• Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of e.g.f. B(x)^k, where B(x) is the e.g.f. of A384689.at n=49A384690
• a(n) = Sum_{i=1..n} (A143293(n) mod prime(i))*A002110(i-1), where A002110 are the primorial numbers, and A143293 give their partial sums.at n=6A392863
• a(n) = Sum_{i=1..n} (A143293(n) mod prime(i))*A002110(i-1), where A002110 are the primorial numbers, and A143293 give their partial sums.at n=7A392863