a(1)=1, a(2)=2; thereafter a(n+1) = Sum_{i=m..n} a(i) where m = (n+1)-k and k is the last digit of a(n), except if k=0, k=1, or k>n then a(n+1) = Sum_{i=1..n} a(i).

A309311

a(1)=1, a(2)=2; thereafter a(n+1) = Sum_{i=m..n} a(i) where m = (n+1)-k and k is the last digit of a(n), except if k=0, k=1, or k>n then a(n+1) = Sum_{i=1..n} a(i).