Indices of zeros of the sequence u(n)=abs(u(n-1)-gcd(u(n-1),n-1)), u(1)=1.

Terms

a(0) =2a(1) =5a(2) =11a(3) =23a(4) =47a(5) =79a(6) =157a(7) =313a(8) =619a(9) =1237a(10) =2473a(11) =4909a(12) =9817a(13) =19603a(14) =39199a(15) =78193a(16) =156019a(17) =311347a(18) =622669a(19) =1244149a(20) =2487739a(21) =4975111a(22) =9950221a(23) =19900399a(24) =39800797a(25) =79601461a(26) =159202369a(27) =318404629a(28) =636788881a(29) =1273577761