135981

Appears in sequences

• Triangular numbers (A000217) with indices A000043.at n=12A139117
• Irregular table read by rows: n-th row lists the 9 n-gonal numbers of a 3 X 3 semimagic square with the smallest magic sum. The terms of each row are arranged in the manner shown in A261816.at n=34A265141
• The first of two consecutive triangular numbers the sum of which is equal to the sum of two consecutive prime numbers.at n=33A298462
• Smallest number m in a set of at least three consecutive triangular numbers with three distinct prime factors.at n=25A349539
• Triangular numbers that are the sum of two distinct nonzero triangular numbers in exactly two ways.at n=23A350368