110215

Appears in sequences

• Triangular numbers whose reverse is prime.at n=23A066751
• Triangular numbers with sum of digits = 10.at n=38A068129
• Terms of A073872 that do not change their position in the rearrangement; i.e., values of A073872(n) which equal n(n+1)/2.at n=35A073873
• a(n) = (9n^4 - 18n^3 + 18n^2 - 9n + 2)/2.at n=12A079903
• Triangular numbers whose sum of aliquot divisors is a prime number.at n=36A083676
• Triangular numbers whose digit reversal is prime; trailing zeros are permitted.at n=30A115704
• The first of two consecutive triangular numbers the sum of which is equal to the sum of two consecutive prime numbers.at n=31A298462
• Numbers that start a run of four consecutive triangular numbers with four distinct prime factors.at n=22A349773
• a(n) = Sum_{1 <= x_1, x_2 <= n} gcd(x_1, x_2, n)^5.at n=9A372927