32004000

Appears in sequences

• a(0) = 21; for n > 0, a(n) is the smallest triangular number which is a (proper) multiple of a(n-1).at n=5A068142
• a(0) = 15; for n > 0, a(n) is the smallest triangular number which is a (proper) multiple of a(n-1).at n=4A068513
• a(n) = (n^6 + n^3)/2.at n=20A071232
• a(n)=2a(n-1) but when sum of digits of 2a(n-1) is greater than 9 take a(n) = largest number < 2a(n-1) which has sum of digits = 9.at n=25A140134
• a(n) = sum of numbers from 1 to pi(n), where pi(n) = A007955(n).at n=19A184390
• Triangular numbers whose sum of digits is 9.at n=37A375824