Terms k of A006521 such that 2*k is a term of A124240.

Terms

a(0) =1a(1) =3a(2) =9a(3) =27a(4) =81a(5) =171a(6) =243a(7) =513a(8) =729a(9) =1539a(10) =2187a(11) =3249a(12) =4617a(13) =6561a(14) =9747a(15) =13203a(16) =13851a(17) =19683a(18) =29241a(19) =39609a(20) =41553a(21) =59049a(22) =61731a(23) =87723a(24) =118827a(25) =124659a(26) =177147a(27) =185193a(28) =250857a(29) =263169