21837

Appears in sequences

• Expansion of 1/((1-x)*(1-2*x)*(1-x^2)).at n=13A011377
• Number of balanced, adequate or average primes < 10^n.at n=6A055206
• a(n) = 4a(n-1) + 3n with a(0) = 0.at n=7A078904
• a(n) = 3*a(n-1) - 3*a(n-2) + 2*a(n-3), with a(0) = 2, a(1) = -3, a(2) = 3.at n=13A135353
• 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), (-1, 1, -1), (1, -1, 0), (1, 1, -1), (1, 1, 1)}.at n=8A149625
• Partial sums of floor(2^n/3).at n=14A178420
• Numerator of sum(i=1..n, 3*i/4^i ).at n=6A215712
• Expansion of Product_{k>=1} (1 + (1 + x + x^2) * x^k).at n=31A309173
• Nonprime numbers k of the form 4*m+1 such that Sum_{j=0..k-1} 2^j * binomial(3*j, j) == 1 (mod k).at n=35A373747
• Number of sequences over {0,1,...,n-1} containing no two consecutive blocks with the same average.at n=5A380000