190036

Appears in sequences

• Triangular numbers such that both the number formed by the first floor((k+1)/2) digits and the remaining part (if any) are triangular numbers, where k is the number of digits.at n=17A068821
• Smallest triangular number beginning with the n-th triangular number other than itself.at n=18A072517
• Numbers k such that the symmetric representation of sigma(k) has only two parts and they meet at the center of the Dyck path.at n=31A262259
• Triangular numbers k such that phi(k) is also a triangular number, where phi(k) is the Euler totient function (A000010).at n=4A287472
• a(1)=1; thereafter, a(n+1) = Sum_{d divides n} (n!/(d!*(n/d)!))*a(d).at n=10A295577
• The numbers appearing in the first layer of the number stack in A370193.at n=20A374496