47817

Appears in sequences

• a(1) = 1, a(n) = a(n-1) + phi(a(n-1)).at n=21A074693
• Long leg of primitive Pythagorean triangles having legs that add up to a square, sorted on hypotenuse.at n=34A089548
• Denominators of e.g.f.: -cot(arctanh(x)), odd powers only.at n=21A102065
• Denominators of e.g.f. sec(arccosh(x)) = cosec(arcsinh(x)).at n=21A102074
• a(n) = (9/2)*(n-1)*(n-2)*(n-3).at n=23A134171
• Number of ways to place zero or more nonadjacent 1,1 2,1 3,0 3,1 3,2 3,3 4,2 5,2 polyhexes in any orientation on a planar nXnXn triangular grid.at n=8A155372
• Numbers n such that n is the mean value of phi(n) and reversal(n).at n=4A178326
• a(n) = 9*a(n-1) - 4*a(n-2), with a(0)=0, a(1)=1.at n=6A190981
• Number of (w,x,y,z) with all terms in {1,...,n} and w > x < y >= z.at n=22A212501
• Integers k such that k = Sum k/(p_i + j), where p_i are the prime factors of k (with multiplicity). Case j = 1.at n=34A380889