168421

Appears in sequences

• Triangle of Gaussian binomial coefficients [ n,k ] for q = 20.at n=16A022184
• Triangle of Gaussian binomial coefficients [ n,k ] for q = 20.at n=19A022184
• a(n) = n^4 + n^3 + n^2 + n + 1.at n=20A053699
• Sum of distinct powers of 20; i.e., numbers with digits in {0,1} base 20; i.e., write n in base 2 and read as if written in base 20.at n=31A063012
• a(n) = (20^n - 1)/19.at n=5A064108
• Successive left concatenation of floor(k/2) beginning with n until we reach 1.at n=15A068657
• Let P(k) = floor(k/2). Start with n, apply P repeatedly until reach 1. a(n) = concatenation of numbers obtained.at n=30A083177
• a(n) is the reverse concatenation of divisors of n.at n=15A176558
• a(n) = A176558(A175354(n)) = numbers m as reverse concatenations of divisors of numbers from A175354, where A175354 = numbers k such that reverse concatenations of divisors of k are nonprimes.at n=11A176588
• a(n) = 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4.at n=18A258978
• Number of (n+1) X (1+1) 0..4 arrays with each row and column divisible by 13, read as a base-5 number with top and left being the most significant digits.at n=19A263434
• Let the binary expansion of n be [b_d, b_{d-1}, ..., b_3, b_2, b_1, b_0]_2, where (if n>0) b_d = 1, b_i = 0 or 1 for i<d. To get a(n) concatenate the decimal numbers 2^(b_i) (if b_i = 1) or 0 (if b_i = 0).at n=31A302205