567645

Appears in sequences

• Triangular numbers such that the product of digits is also a (positive) triangular number.at n=36A069077
• Triangular numbers that are one-third of another triangular number: T(m) such that 3*T(m) = T(k) for some k.at n=6A076139
• Numbers that are both triangular and pentagonal of the second kind.at n=3A108281
• Numbers n such that phi(n)*sigma(n)=phi(n-1)*sigma(n-1) (phi is the Euler totient function A000010 and sigma is the sum-of-divisors function A000203).at n=16A140790
• Triangle T(n, k, m) = t(n, m)/(t(k, m)*t(n-k, m)), where t(n, k) = Product_{j=1..n} p(j, k+1), p(n, x) = Sum_{j=0..n} (-1)^j*A053122(n, j)*x^j, and m = 5, read by rows.at n=30A156599
• Triangle T(n, k, m) = t(n, m)/(t(k, m)*t(n-k, m)), where t(n, k) = Product_{j=1..n} p(j, k+1), p(n, x) = Sum_{j=0..n} (-1)^j*A053122(n, j)*x^j, and m = 5, read by rows.at n=33A156599
• Numbers k such that k^3 +/- k +/- 1 are prime for all four possibilities.at n=27A236764
• Triangular numbers n such that sigma(n) is a square number.at n=28A256151
• Positive hexagonal numbers (A000384) that are other hexagonal numbers divided by 3.at n=1A259210
• Odd multiplicative orders of 2+-i modulo primes p == 3 (mod 4).at n=12A385217