121278

Appears in sequences

• Triangular numbers that are half other triangular numbers.at n=4A075528
• Sequence of distinct least triangular numbers such that the arithmetic mean of the first n terms is also a triangular number. Initial term is 0.at n=25A236415
• Number of n X 7 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=16A280439
• Triangular numbers which are products of five distinct primes.at n=30A357590