189420

Appears in sequences

• Fibonacci sequence beginning 0, 28.at n=20A022362
• Smallest triangular number which is a multiple (>1) of the n-th triangular number.at n=39A068084
• Triangular numbers that are the product of two triangular numbers greater than 1.at n=33A188630
• Numbers with prime factorization pqrstu^2.at n=25A189985
• Triangular numbers which have one or more occurrences of exactly six different digits.at n=22A241789
• Triangular numbers that can be represented as a sum of two distinct triangular numbers, and as a product of two triangular numbers greater than 1.at n=15A295768
• Numbers that are product of a hexagonal number (A000384) and a square pyramidal numbers (A000330) in at least two ways.at n=26A306121
• Trajectory of 397 under the map A340008: n -> n/2 if n is even, n-> n^2 - 1 if n is an odd prime, otherwise n -> n - 1.at n=14A340419
• Numbers that are equal to the product of the numerator and denominator of the harmonic mean of their divisors.at n=18A348828
• a(n) = A375251(n) / A010790(n) = denominator(W1([n], x)) / (n!*(n - 1)!), where W1([n], x) is the first Sylvester wave for parts in [n].at n=40A375250
• a(0) = 397; a(n+1) = a(n)^2 if a(n) is prime, floor(a(n)/2) otherwise.at n=12A376801