Positions of 4's in A347381.

Terms

a(0) =21a(1) =26a(2) =30a(3) =32a(4) =33a(5) =36a(6) =37a(7) =40a(8) =42a(9) =44a(10) =48a(11) =49a(12) =50a(13) =54a(14) =60a(15) =65a(16) =75a(17) =80a(18) =84a(19) =90a(20) =91a(21) =112a(22) =120a(23) =125a(24) =126a(25) =153a(26) =162a(27) =175a(28) =176a(29) =198