81090

Appears in sequences

• a(2n+1) = a(2n) + a(2n-1), a(2n) = 2*a(2n-1) + a(2n-2); a(n) = n for n = 0, 1.at n=18A048788
• a(n) = 4*a(n-1) - a(n-2), with a(0) = 0, a(1) = 2.at n=9A052530
• Limit of the sequence obtained from S(0) = (1,1) and, for n > 0, S(n) = I(S(n-1)), where I consists of inserting, for i = 1, 2, 3..., the term a(i) + a(i+1) between any two terms for which 7*a(i+1) <= 11*a(i).at n=17A082630
• a(2*n+1) = 9*a(n), a(2*n+2) = 10*a(n) + a(n-1).at n=41A116555
• a(n) = 3*n^3 + 3*n.at n=30A119536
• The pairs (x,y) such that (x^2 + y^2)/(x*y + 1) is a perfect square, i.e., 4.at n=17A162959
• The pairs (x,y) such that (x^2 + y^2)/(x*y + 1) is a perfect square, i.e., 4.at n=18A162959
• a(n) = a(n-1) + (if a(n-1) is odd a(n-2) else a(n-3)) with a(0) = 0, a(1) = 1.at n=27A254308
• Maximal term of TRIP-Stern sequence of level n corresponding to permutation triple (e,23,e).at n=33A271488
• Those primitive elements of A337386 that have exactly one primitive nondeficient divisor (A006039).at n=33A341604
• Expansion of g.f.: 1/Sum_{p prime} x^p.at n=26A352476
• Square array, read by descending antidiagonals, where each row n comprises the integers w >= 1 such that A000037(n)*w^2+4 is a square.at n=46A378908
• Square array read by descending antidiagonals: A(n,k) is the number of fixed n-dimensional (n,2)-polyominoids, n >= 2, of size k >= 1.at n=24A385715