21346

Appears in sequences

• Number of graphs on n nodes with 3 cliques.at n=21A005289
• Numbers k such that the continued fraction for sqrt(k) has period 47.at n=28A020386
• Number of partitions of n with equal number of parts congruent to each of 1, 2 and 3 (mod 4).at n=62A046769
• Number of partitions of n with equal nonzero number of parts congruent to each of 1, 2 and 3 (mod 4).at n=62A046781
• Numbers k such that k+1, k^2+1 and k^4+1 are primes.at n=45A070325
• Numbers k such that sigma(sigma(k) - k) = phi(sigma(k) + k).at n=16A074886
• Expansion of q^(-1/3) * eta(q^6)^2 / (eta(q) * eta(q^3)) in powers of q.at n=34A097197
• Number of distinct products i*j*k*l for 1 <= i <= j <= k <= l <= n.at n=39A100437
• Expansion of psi(-q^3) / f(q) where psi(), f() are Ramanujan theta functions.at n=34A139135
• Number of (n+2) X (5+2) 0..3 arrays with every 3 X 3 subblock row and column sum not 2 3 6 or 7 and every diagonal and antidiagonal sum 2 3 6 or 7.at n=7A251891
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 606", based on the 5-celled von Neumann neighborhood.at n=37A273206
• a(1) = 1; a(n) = Sum_{k=1..n} a(ceiling((n-1)/k)).at n=41A290845
• Start with a 2 X n array of squares, join every vertex on top edge to every vertex on bottom edge; a(n) = one-half the number of cells.at n=22A355902
• Expansion of g^5/(1 + x*g)^2, where g = 1+x*g^2 is the g.f. of A000108.at n=8A391408