133327domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumbers k such that the k-th triangular number contains only digits {1,2,8}.at n=18A119108a(1) = 1, then subtract, add, and multiply 2, 3, 4; 5, 6, 7; ... in that order.at n=16A362269Prime numbersat n=12444