Geometric mean of digits = 4 and digits are in nondecreasing order.

Terms

a(0) =4a(1) =28a(2) =44a(3) =188a(4) =248a(5) =444a(6) =1488a(7) =2288a(8) =2448a(9) =4444a(10) =12888a(11) =14488a(12) =22488a(13) =24448a(14) =44444a(15) =118888a(16) =124888a(17) =144488a(18) =222888a(19) =224488a(20) =244448a(21) =444444a(22) =1148888a(23) =1228888a(24) =1244888a(25) =1444488a(26) =2224888a(27) =2244488a(28) =2444448a(29) =4444444