990528

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=25A068821
• Triangular numbers which are 10-almost primes.at n=11A101744
• First differences of A036449, triangular numbers by definition.at n=10A189475
• a(n) = (m(n)^2 + 3)*(m(n)^2 + 7)/32, where m(n) = 2*n - 1.at n=37A336535