180000

Appears in sequences

• Number of reversible strings with n labeled beads of 5 colors, no palindromes of more than 1 bead.at n=4A032072
• Sum of digits of numbers between 0 and (10^n)-1.at n=4A034967
• Triangle whose (i,j)-th entry is binomial(i,j)*5^(i-j)*12^j.at n=17A038254
• Triangle whose (i,j)-th entry is binomial(i,j)*12^(i-j)*5^j.at n=18A038331
• For n>3: a(n) is a multiple of three distinct earlier terms.at n=28A060301
• Triangle of coefficients of polynomials (rising powers) useful for convolutions of A000204(n+1), n >= 0 (Lucas numbers).at n=21A061189
• Powerful numbers (definition 1) sandwiched between twin primes.at n=17A113839
• Even refactorable numbers k such that the number r of odd divisors of k and the number s of even divisors of k are both odd divisors of k.at n=37A120361
• Denominator of Sum_{i=1..n} i!/(i^i).at n=5A121564
• Averages of twin prime pairs k such that k*2 and k/2 are squares.at n=17A154670
• a(n) = n^2*(n+1)^2/2.at n=24A163102
• Totally multiplicative sequence with a(p) = 10*(p+3) for prime p.at n=17A167329
• Integers that can be generated with a C/C++ expression that is two or more characters shorter than their decimal representation.at n=17A168651
• Number of ways to place 2 nonattacking bishops on an n X n toroidal board.at n=24A177755
• Triangle read by rows: T(n,k) is the number of weighted lattice paths in L_n having k returns to the horizontal axis (both from above and below). The members of L_n are paths of weight n that start at (0,0) , end on the horizontal axis and whose steps are of the following four kinds: an (1,0)-step with weight 1, an (1,0)-step with weight 2, a (1,1)-step with weight 2, and a (1,-1)-step with weight 1. The weight of a path is the sum of the weights of its steps.at n=52A182898
• Expansion of phi_{5, 4}(x) where phi_{r, s}(x) = Sum_{n, m>0} m^r * n^s * x^{m*n}.at n=10A280022
• Base-10 complementary numbers: n equals the product of the 10's complement of its digits.at n=16A294090
• Triangle read by rows: T(n,k) is the sum of the number of the arrangements of p_1 1's, p_2 2's, ..., p_k k's (p_1 + p_2 + ... + p_k = n and p_1 >= p_2 >= ... >= p_k) avoiding equal consecutive terms, where 1 <= k <= n.at n=50A321686
• Numbers k such that sum of digits (k) and sum of digits (k^2) is 9.at n=16A325450
• Numbers that are highly powerful in Gaussian integers.at n=29A335853