The (10^n)-th 4-almost prime.

Terms

a(0) =16a(1) =88a(2) =693a(3) =5958a(4) =54328a(5) =511725a(6) =4922511a(7) =47997635a(8) =472514554a(9) =4683086217a(10) =46636297326a(11) =466032880556