a(1) = 7, 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).

A063384

a(1) = 7, 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) =7a(1) =17a(2) =117a(3) =913a(4) =1183a(5) =1391a(6) =13107a(7) =51257a(8) =151257a(9) =381397a(10) =577661a(11) =4911789a(12) =29116879a(13) =112646989a(14) =536920981a(15) =1928258999a(16) =11928258999a(17) =25227472837a(18) =46275452231a(19) =212892173679a(20) =370964057893

External references