21178

Appears in sequences

• Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite SGT = Sigma-2 [Si64O128].4R starting with a T1 atom.at n=13A019235
• Numbers k such that the continued fraction for sqrt(k) has period 77.at n=25A020416
• Canonically 2-indecomposable posets with n antichains.at n=27A072407
• G.f.: A(x) = Product_{n>=1} 1/(1 - 2^n*x^n)^(2/2^n).at n=12A110152
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (-1, 0, 0), (0, 1, 0), (1, 0, 0)}.at n=9A149907
• Number of nonempty subsets of {1, 2, ..., n} with <=5 pairwise coprime elements.at n=33A187266
• The cube of the g.f. equals the g.f. of A196306.at n=13A196307
• Number of n X 2 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 3 binary array having a sum of one or less, with rows and columns of the latter in lexicographically nondecreasing order.at n=26A227161
• a(n) = 10^(prime(n)-1) mod prime(n)^2.at n=41A265012
• Numbers m such that phi(sum of the divisors of m) = phi(sum of the distinct prime divisors of m) where phi is the Euler totient function.at n=16A282515
• Number of lattice paths from (0,0) to (n,n) that do not go above the diagonal x=y and consist of steps (h,v) with min(h,v) > 0 and gcd(h,v) = 1.at n=11A308113
• Number of positive solutions to (x_1)^2 + (x_2)^2 + ... + (x_8)^2 <= n^2.at n=4A341427
• a(n) is the number of 5 element sets of distinct integer-sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units formed by directly binary space partitioning 3-trapezoid sets without forming 4-trapezoid sets.at n=38A391203