4215120

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=24A048788
• a(n) = 4*a(n-1) - a(n-2), with a(0) = 0, a(1) = 2.at n=12A052530
• a(n) = 14*a(n-1) - a(n-2); a(0) = 0, a(1) = 8.at n=6A067900
• 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=23A082630
• Numbers k such that k^2 + 1 is a Sarrus number (pseudoprime to base 2).at n=20A135590
• Expansion of (1-2x-3x^2+x^3-x^5)/(1+4x^3+x^6).at n=34A157126
• The pairs (x,y) such that (x^2 + y^2)/(x*y + 1) is a perfect square, i.e., 4.at n=23A162959
• The pairs (x,y) such that (x^2 + y^2)/(x*y + 1) is a perfect square, i.e., 4.at n=24A162959
• 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=36A254308
• Triangular array read by rows. T(n,k) is the number of n X n matrices over GF(3) such that the sum of the dimensions of its eigenspaces taken over all its eigenvalues is k, 0 <= k <= n, n >= 0.at n=13A346421