Numbers k such that the concatenation 1,2,3,...,(k-1) is divisible by k.

Terms

a(0) =1a(1) =3a(2) =9a(3) =27a(4) =69a(5) =1053a(6) =1599a(7) =2511a(8) =8167a(9) =21371a(10) =73323a(11) =225681a(12) =313401a(13) =362703a(14) =371321a(15) =1896939a(16) =2735667a(17) =3426273a(18) =3795093a(19) =5433153a(20) =302278903a(21) =1371292077a(22) =19755637749a(23) =23560349643a(24) =33184178631