a(1) = 9, 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).
A063423
a(1) = 9, 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) =9a(1) =33a(2) =311a(3) =1311a(4) =2357a(5) =12357a(6) =91373a(7) =191373a(8) =273701a(9) =594639a(10) =966071a(11) =3792549a(12) =7714919a(13) =18474177a(14) =36158059a(15) =217166627a(16) =415296747a(17) =1269327263a(18) =8581147923a(19) =85531003291a(20) =307572780863a(21) =417501775143a(22) =594709702027
External references
- oeis: A063423