19300

Appears in sequences

• a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t(n)=2*n+1 (odd numbers).at n=47A023865
• a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n-k+1), where k = floor(n/2), s = natural numbers, t = odd natural numbers.at n=46A024862
• Card-matching numbers (Dinner-Diner matching numbers).at n=27A059062
• Card-matching numbers (Dinner-Diner matching numbers).at n=44A059066
• a(n) = n*(n+1)*(8*n + 1)/6.at n=24A132124
• Number of distinct solutions of sum{i=1..7}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1.at n=5A180789
• T(n,k)=number of distinct solutions of sum{i=1..k}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 1..n-1.at n=71A180793
• Number of cyclotomic cosets of 13 mod 10^n.at n=49A221855
• Number of nX4 0..3 arrays with every row having the same least squares slope fit to a straight line, and every column the same least squares slope fit to a straight line, with a single point array taken as having zero slope.at n=3A223064
• T(n,k)=Number of nXk 0..3 arrays with every row having the same least squares slope fit to a straight line, and every column the same least squares slope fit to a straight line, with a single point array taken as having zero slope.at n=24A223066
• Expansion of Product_{k>=1} ((1 - k*x^k)/(1 + k*x^k)).at n=42A292317
• Practical numbers z such that z^2 = x^2 + y^2 for some practical numbers x and y with gcd(x,y,z) = 4.at n=32A294112
• For any k, the cumulative sum a(1) + a(2) + a(3) + ... + a(k) shares at least five digits with a(k). Lexicographically first sequence of positive integers without duplicate terms having this property.at n=23A326640
• Sum of the areas of all r X s rectangles such that r < s, r + s = 2n and (s - r) | (s * r).at n=47A333754
• Irregular table read by rows, T(n, k) is the rank of the k-th Seidel permutation of {1,...,n}, permutations sorted in lexicographical order.at n=38A347600
• Number of cells in a regular 7-gon after n generations of mitosis.at n=23A349808
• a(n) = Sum_{d|n} (n/d)^(n-n/d) * binomial(d+n-1,n).at n=7A363664
• Triangle read by rows: T(n,k) is the number of open meanders with 2n crossings and k exterior top arches, 0 <= k <= n.at n=40A380369