18335
domain: N
Appears in sequences
- a(n) = prime(n)*(prime(n-1)-1)/2.at n=41A014302
- Divide primes into groups with prime(n) elements and add together.at n=9A034958
- n! has a palindromic prime number of digits.at n=25A035067
- Number of rooted trees with n nodes with every leaf at height 10.at n=19A048815
- Numbers k such that k! - (k-1)! - 1 is prime.at n=24A049433
- Row sums of triangle A084408.at n=28A084411
- One-fourth of partial sums of A153976.at n=18A153977
- Number of cyclotomic cosets of 11 mod 10^n.at n=47A220021
- a(n) gives the odd leg of one of the two Pythagorean triangles with hypotenuse A080109(n) = A002144(n)^2. This is the smaller of the two possible odd legs.at n=19A253802
- Expansion of (1-sqrt(1-4*x^4/(1-x)^4))/(2*x^4*(1-x)).at n=12A270784
- Numbers whose Euler totient function is equal to the product of the number of divisors of their k first powers, for some k.at n=37A283759
- Number of n X 2 0..1 arrays with each 1 adjacent to 3, 4 or 5 king-move neighboring 1s.at n=12A296984
- Expansion of Sum_{k>=1} (-1 + Product_{j>=1} 1/(1 - x^(k*j))^j).at n=16A302549