Indices of primes in sequence defined by A(0) = 61, A(n) = 10*A(n-1) + 21 for n > 0.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =17a(5) =18a(6) =22a(7) =23a(8) =33a(9) =40a(10) =55a(11) =63a(12) =83a(13) =148a(14) =271a(15) =754a(16) =1271a(17) =2397a(18) =2685a(19) =4799a(20) =5197a(21) =6216a(22) =8736a(23) =12387a(24) =12390a(25) =19701a(26) =42403