Position of n-th 4 in A030567.

Terms

a(0) =4a(1) =14a(2) =26a(3) =38a(4) =43a(5) =45a(6) =47a(7) =49a(8) =50a(9) =51a(10) =53a(11) =62a(12) =78a(13) =96a(14) =114a(15) =132a(16) =139a(17) =142a(18) =145a(19) =148a(20) =150a(21) =151a(22) =154a(23) =168a(24) =186a(25) =204a(26) =222a(27) =240a(28) =247a(29) =250