18480

Appears in sequences

• a(n) = (4*n)! / ((2*n)!*n!^2).at n=3A000897
• Number of compositions of n into a sum of odd primes.at n=44A002124
• Triangle of coefficients of Legendre polynomials 2^n P_n (x).at n=28A008556
• Area of more than one Pythagorean triangle.at n=16A009127
• a(n) = n*(n+1)*(2*n+1)*(3*n+1)*(4*n+1)/6.at n=5A011197
• Expansion of e.g.f. sec(sin(x)*log(x+1)).at n=8A012288
• Numbers k such that sigma(k)/phi(k) sets a new record.at n=20A018894
• a(n) = 5*(n+1)*binomial(n+4,6).at n=5A027802
• a(n) = 14*(n+1)*binomial(n+4,8).at n=3A027804
• Number of different words that can be formed from an n X n grid of letters, reading horizontally, vertically or diagonally.at n=17A034720
• Smallest number that is palindromic (with at least 2 digits) in n bases.at n=42A037183
• Denominators of continued fraction convergents to sqrt(439).at n=7A041837
• Expansion of (1-x)/(1-x-3*x^2).at n=13A052533
• Triangle T(n,k) = number of degree-n permutations with k even cycles, k=0..n.at n=37A060523
• a(1)=1, a(2)=2; thereafter, a(n) is the smallest number m not yet in the sequence such that every prime that divides a(n-1) also divides m.at n=30A060735
• Smallest number whose square has (2n - 1)^2 divisors.at n=13A061708
• Triangle read by rows: T(n, k) = [z^k] P(n, z) where P(n, z) = Sum_{k=0..n} binomial(n, k) * Pochhammer(n - k + c, k) * z^k / k! and c = 4.at n=48A062145
• T(n,k) = binomial(n,k)*binomial(n+k,k), 0 <= k <= n, triangle read by rows.at n=48A063007
• Least prime signature numbers that are not a Jordan-Polya number.at n=31A064783
• Index values for new maxima in sequence A007365.at n=24A065932