75726domain: NAppears in sequences25-gonal pyramidal numbers: a(n) = n*(n+1)*(23*n-20)/6.at n=27A256645a(n) = 81*n^2 - 69*n + 24.at n=31A304616a(n) is the smallest positive integer which can be represented as the sum of n distinct nonzero tetrahedral numbers in exactly n ways, or -1 if no such integer exists.at n=32A360217