18884

Appears in sequences

• The limiting sequence [A259095(r(r+1)/2-s,r), s=0,1,2,...,r-1] for very large r.at n=41A005576
• a(n) = floor(n(n-1)(n-2)(n-3)/19).at n=26A011929
• Length of n-th term of A006711.at n=34A022476
• a(n) = Sum_{k=m..n} T(k,n-k), where m = floor((n+1)/2); a(n) is the n-th diagonal-sum of left justified array T given by A027935.at n=25A027947
• a(0)=0, a(1)=1, a(2)=1, a(3)=1, a(n) = a(n-3) + a(n-4) for n > 3.at n=52A079398
• Draw a line through every pair of points with coordinates (x, 1) and (x', 2) with x, x' in 1..n, and then count the number of intersection points above the line y = 2.at n=22A092275
• Numbers n such that (10^n-1)^2-2 is prime.at n=7A100903
• Sequence equals its 4th differences shifted by one index.at n=12A137166
• a(n) = 3*a(n-1)-3*a(n-2)+a(n-3)+a(n-4).at n=16A138653
• Shifts left when Dirichlet convolution (DC:(b,b)->a) applied twice.at n=8A144316
• Square array A(n,k), n>=1, k>=1, read by antidiagonals, with A(1,k)=1 and sequence a_k of column k shifts left when Dirichlet convolution (DC:(b,b)->a) applied k times.at n=53A144324
• Square array A(n,k), n>=1, k>=1, read by antidiagonals, with A(1,k)=1 and sequence a_k of column k shifts left when Dirichlet convolution with a_k (DC:(b,a_k)->a) applied k times.at n=63A144823
• Least number k having n representations as the sum of the minimal number of cubes A002376(k).at n=21A163490
• a(j) = maximum value of n for each distinct increasing value of (Sum of the quadratic non-residues of prime(n) - Sum of the quadratic residues of prime(n)) / prime(n) for each j.at n=18A166263
• Integers n such that 17+30*n are terms in A172456.at n=15A175103
• Numbers n such that c(n) = p_{2n}, where c(n) is the n-th Chebyshev prime and p_{2n} the 2n-th prime.at n=6A196674
• Smallest m such that the n-th odd prime is the smallest prime for all decompositions of 2*m into two primes.at n=33A208662
• Number of length n+5 0..3 arrays with every six consecutive terms having two times the sum of some two elements equal to the sum of the remaining four.at n=7A249080
• Number of permutations of [n] avoiding the patterns 2-41-3, 3-14-2, 2-14-3, and 3-41-2.at n=9A348351
• a(n) = Sum_{k=1..n-1} tau(k) * sigma_2(n-k).at n=25A374973