Positions of multiples of 3 in A024702.

Terms

a(0) =7a(1) =8a(2) =12a(3) =16a(4) =20a(5) =21a(6) =24a(7) =28a(8) =29a(9) =31a(10) =38a(11) =41a(12) =42a(13) =45a(14) =46a(15) =51a(16) =54a(17) =57a(18) =58a(19) =63a(20) =72a(21) =75a(22) =78a(23) =83a(24) =84a(25) =87a(26) =91a(27) =93a(28) =96a(29) =98