26531

Appears in sequences

• a(n) = 6*a(n-2) - a(n-4).at n=13A006452
• a(n) = (n^3 + 2*n)/3.at n=43A006527
• a(n) = 6*a(n-1) - a(n-2), n >= 2, a(0)=1, a(1)=4.at n=6A038723
• a(n) = (2*n+1)*(4*n^2+4*n+3)/3.at n=21A057813
• Starting positions of strings of three 4's in the decimal expansion of Pi.at n=19A083615
• a(n) is the number of terms in the expansion of (x+y-z)*(x^2+y^2-z^2)*(x^3+y^3-z^3)*...*(x^n+y^n-z^n).at n=20A086817
• Dispersion of the Beatty sequence ([r*n]: n >= 1), where r = 3 + 8^(1/2): square array D(n,m) (n, m >= 1), read by ascending antidiagonals.at n=41A120858
• One third of product plus sum of three consecutive nonnegative integers; a(n)=(n+1)(n^2+2n+3)/3.at n=42A167875
• a(n) = prime(n)^2 - n.at n=37A182174
• Sequences A006452 and A216134 interlaced.at n=26A216162
• Largest number in a 6-tuple (a,b,c,d,e,f) of positive integers satisfying the Markoff(6) equation a^2 + b^2 + c^2 + d^2 + e^2 + f^2 = 3*a*b*c*d*e*f.at n=41A227204
• Expansion of (1 + 6*x + 17*x^2 - x^3 - 3*x^4)/(1 - 6*x^2 + x^4).at n=10A227792
• One of the two successive approximations up to 7^n for the 7-adic integer sqrt(-6). These are the numbers congruent to 1 mod 7 (except for the initial 0).at n=6A290800
• a(n) = sqrt(A299921(n)).at n=19A301318
• Triangle of optimist numbers T(n,k) (n >= 1, 0 <= k <= n-1) read by rows: permutations needing k steps to be sorted by the "optimist" algorithm.at n=41A345453
• G.f. A(x) satisfies A( x*(1+x)/A(x)^2 ) = 1 + x.at n=8A383563