Numbers k that divide s(k), where s(1)=1, s(j)=7*s(j-1)+j.

Terms

a(0) =1a(1) =3a(2) =7a(3) =9a(4) =21a(5) =27a(6) =57a(7) =63a(8) =81a(9) =171a(10) =189a(11) =203a(12) =243a(13) =333a(14) =399a(15) =513a(16) =567a(17) =609a(18) =729a(19) =999a(20) =1083a(21) =1197a(22) =1539a(23) =1701a(24) =1827a(25) =2187a(26) =2331a(27) =2943a(28) =2997a(29) =3249