21489003

Appears in sequences

• a(n) = 4*a(n-1) - a(n-2), with a(0) = 1, a(1) = 1.at n=14A001835
• a(n) = 4*a(n-2) - a(n-4) for n > 1, a(n) = n for n = 0, 1.at n=27A002530
• a(n) = (1 + a(n-1)*a(n-2))/a(n-3), a(0) = a(1) = a(2) = 1.at n=28A005246
• 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=27A048788
• a(n) = 4*a(n-1) - a(n-2) with a(1) = 1, a(2) = 3.at n=13A079935
• Expansion of x*(1 + x)*(1 - 3*x^2)/(1 - 4*x^2 + x^4).at n=28A122573
• Expansion of x*(1 + x)*(1 - 3*x^2)/(1 - 4*x^2 + x^4).at n=29A122573
• Number of Khalimsky-continuous functions with a three-point codomain.at n=24A131887
• Interleave denominators and numerators of convergents to sqrt(3).at n=39A140827
• a(n) gives y-values solving the Diophantine equation 2*x^2 + (x-1)^2 = y^2 for positive x.at n=6A189356
• 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=40A254308
• a(n) = numerator(r(n)) where r(n) = (((1/2)*(sqrt(3) + 1))^n - ((1/2)*(sqrt(3) - 1))^n * cos(Pi*n))/sqrt(3).at n=27A305491
• Diagonals of a Euclidian solid such that there exists a Pythagorean quadruple d^2=a^2+b^2+c^2 that is more cube-like than any prior value of d.at n=18A375098
• a(0) = 1, a(n+1) = 6*a(n)^3 - 3*a(n).at n=3A378683