246753

Appears in sequences

• Tritriangular numbers: a(n) = binomial(binomial(n,2),2) = n*(n+1)*(n-1)*(n-2)/8.at n=38A050534
• Number of step cyclic shifted sequences using a maximum of five different symbols.at n=9A056413
• Numbers k such that phi(k)/lambda(k) increases to a record value, where phi(k) is the Euler totient function (A000010) and lambda(k) is the Carmichael lambda function (A002322).at n=29A066605
• Triangular numbers whose digits can be rearranged to form a substring of 123456789012345678901234....at n=23A068804
• a(n) = n*(n+1)*(n^2+n+1)/2.at n=26A110450
• a(n) = (9/2)*(n-1)*(n-2)*(n-3).at n=39A134171
• a(n) = smaller member of n-th pair of distinct, positive, triangular numbers whose sum and difference are also triangular numbers.at n=26A185129
• Triangular numbers that are the product of two triangular numbers greater than 1.at n=35A188630
• Triangular numbers (A000217) whose arithmetic derivative (A003415) is also a triangular number.at n=7A351130