51480

Appears in sequences

• a(n) = (2n+1)!/n!^2.at n=7A002457
• Expansion of e.g.f. (1 - x)^x.at n=11A007114
• a(n) = (1/C(2n,0) - 1/C(2n,1) + ... + d/C(2n,2n))*L, where d = (-1)^2n, L = LCM{C(2n,0), C(2n,1),..., C(2n,2n)}.at n=6A025535
• Numbers k whose decimal representation, read as a base-22 value and divided by k, yields an integer.at n=29A032575
• Partial sums of A027818.at n=9A034266
• Distinct even numbers in the triangle of denominators in Leibniz's Harmonic Triangle.at n=46A046204
• First numerator and then denominator of central elements of Leibniz's Harmonic Triangle.at n=15A046212
• Array T(i,j) = binomial(-1/2-i,j)*(-4)^j, i,j >= 0 read by antidiagonals going down.at n=37A046521
• a(n) = Sum_{j=0..n} A047072(j, n-j).at n=18A047073
• Maximal value of products of partitions of n into powers of distinct primes (1 not considered a power).at n=46A051703
• A convolution triangle of numbers based on A000984 (central binomial coefficients of even order).at n=47A054335
• a(n) = (n+1)*binomial(n+8, 8).at n=7A056003
• Swinging factorial, a(n) = 2^(n-(n mod 2))*Product_{k=1..n} k^((-1)^(k+1)).at n=15A056040
• a(n) = n!/(k!)^2, where k is the largest number such that (k!)^2 divides n!.at n=14A056042
• Triangle (0 <= k <= n) read by rows: T(n, k) is the number of Schröder paths from (0,0) to (2n,0) having k peaks.at n=47A060693
• T(n,k) = binomial(n,k)*binomial(n+k,k), 0 <= k <= n, triangle read by rows.at n=43A063007
• Numbers expressible as (a^2-1)(b^2-1) in at least 2 distinct ways (b>=a>1).at n=30A063067
• a(n) is the least common multiple of numbers in {1,2,3,...,n-1} which do not divide n.at n=13A067391
• Numbers n such that sigma(n)^2 > 9*sigma_2(n) where sigma_2(n) is the sum of squares over the divisors of n.at n=29A068378
• Irregular triangle of the Fibonacci polynomials of A011973 multiplied diagonally by the Catalan numbers.at n=37A068763