a(1) = 3, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).

A063269

a(1) = 3, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).

Terms

    a(0) =3a(1) =13a(2) =113a(3) =1113a(4) =2153a(5) =12153a(6) =34051a(7) =172003a(8) =1311313a(9) =3473779a(10) =5365543a(11) =16913173a(12) =34014973a(13) =229148537a(14) =479347809a(15) =1807726517a(16) =11807726517a(17) =20529575173a(18) =69833293981a(19) =179443389167a(20) =230839777353a(21) =376946592451

External references