81406

Appears in sequences

• Numbers of the form prime(n) + prime(n+1) - 2 that are also triangular numbers, T(k) = k(k+1)/2.at n=30A110891
• Triangular numbers all of whose digits are nonprimes.at n=35A111484
• Smallest triangular number whose decimal expansion ends (nontrivially) with the n-th triangular number.at n=27A229262
• Numbers that start a run of four consecutive triangular numbers with four distinct prime factors.at n=14A349773
• Hexagonal numbers that are products of exactly four distinct primes.at n=35A381920