1975354domain: NAppears in sequencesp*(p+1)*(p+2)/6 where (p,p+2) are twin primes.at n=15A126249Tetrahedral numbers k*(k+1)*(k+2)/6 such that exactly two of k, k+1, and k+2 are prime.at n=17A152916Tetrahedral (or triangular pyramidal) numbers which are products of four distinct primes.at n=26A353027