19503

Appears in sequences

• a(n) = n*(11*n^2 - 5)/6.at n=22A004467
• Strong pseudoprimes to base 100.at n=29A020326
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 29 ones.at n=5A031797
• Triangular numbers (A000217) with prime indices.at n=44A034953
• Odd triangular numbers with prime indices.at n=21A034954
• a(n) = 25*n*(n + 1)/2 + 3.at n=39A061793
• Numbers n such that Fibonacci(n) is not squarefree, but for all proper divisors k of n, Fibonacci(k) is squarefree.at n=38A065069
• Least m such that sqrt(m) has a period 2n continued fraction expansion whose palindrome part concatenates to a palindromic prime.at n=21A072135
• (Largest Matula-Goebel number encoding a tree with n nodes) - (smallest Matula-Goebel number encoding a tree with n nodes).at n=8A091233
• Triangular numbers for which the sum of the digits is a heptagonal number.at n=22A117312
• Triangular numbers for which the sum of the digits equals the sum of the digits of the next triangular number.at n=11A117511
• Numbers which are both lucky and triangular.at n=36A118565
• Triangular numbers n*(n+1)/2 with n prime and n+1 nonprime.at n=43A144519
• Triangular numbers p*(p+1)/2 with p prime such that 1+(number of prime factors of p+1) is prime.at n=19A144549
• a(n) = 1*3*5 + 3*5*7 + 5*7*9 + ... (n terms).at n=9A196506
• Number of n X n 0..2 arrays of the median of the corresponding element, the element to the east and the element to the south in a larger (n+1)X(n+1) 0..2 array.at n=2A228971
• Number of n X 3 0..2 arrays of the median of the corresponding element, the element to the east and the element to the south in a larger (n+1) X 4 0..2 array.at n=2A228973
• T(n,k) = number of nXk 0..2 arrays of the median of the corresponding element, the element to the east and the element to the south in a larger (n+1)X(k+1) 0..2 array.at n=12A228977
• Number of (n+1)X(n+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with values 0..2 introduced in row major order.at n=3A231256
• Number of (n+1)X(4+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with values 0..2 introduced in row major order.at n=3A231259