20831

Appears in sequences

• s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = A000201 (lower Wythoff sequence), t = A001950 (upper Wythoff sequence).at n=37A025119
• a(n) = a(n-1) + 2*n^2 with a(1) = 1.at n=30A112524
• The Wiener index of a benzenoid consisting of a linear chain of n hexagons.at n=14A143938
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (0, 0, -1), (0, 0, 1), (0, 1, 1), (1, 1, 0)}.at n=7A151178
• A symmetrical triangle sequence:q=3;c(n,q)=Product[1 - q^i, {i, 1, n}];t(n,m,q)=-Eulerian[n + 1, m] + 2*c(n, q)/(c(m, q)*c(n - m, q)).at n=23A176428
• A symmetrical triangle sequence:q=3;c(n,q)=Product[1 - q^i, {i, 1, n}];t(n,m,q)=-Eulerian[n + 1, m] + 2*c(n, q)/(c(m, q)*c(n - m, q)).at n=25A176428
• Define a pair of sequences c_n, d_n by c_0=0, d_0=1 and thereafter c_n = c_{n-1}+d_{n-1}, d_n = c_{n-1}+4*n+2; sequence here is c_n.at n=16A192751
• Number of length 3 0..n arrays with each partial sum starting from the beginning no more than one standard deviation from its mean.at n=37A244791
• Smallest number such that the sum of the digits of n * a(n) is greater than n.at n=47A269333
• Relative of Hofstadter Q-sequence: a(n) = max(0, n+20830) for n <= 0; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 0.at n=1A283887
• a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = -1, a(1) = -1, a(2) = 2, a(3) = 1.at n=18A295852
• G.f.: Sum_{n>=0} x^n * ( (1+x)^n + (1-x)^n )^n / 2^n.at n=11A301308
• a(n) = ceiling(sqrt(2*a(n-1)*a(n-2))), a(1) = a(2) = 1.at n=41A318053