a(n) = k such that the k-th triangular number is A068808(n).

Terms

a(0) =1a(1) =2a(2) =3a(3) =7a(4) =11a(5) =12a(6) =27a(7) =31a(8) =56a(9) =107a(10) =109a(11) =132a(12) =309a(13) =343a(14) =627a(15) =968a(16) =1332a(17) =1891a(18) =3129a(19) =3434a(20) =5291a(21) =5656a(22) =8831a(23) =13332a(24) =18972a(25) =19492a(26) =28248a(27) =37067a(28) =58309a(29) =107516