128271domain: NAppears in sequencesTriangular numbers with square pyramidal indices.at n=11A076767Concatenation of triangular number k and its 10's complement is prime.at n=28A108970a(n) = n*(n+1)*(n^2+n+1)/2.at n=22A110450Smallest triangular number that is pandigital in base n.at n=5A260117