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%I #16 Mar 24 2015 17:52:30
%S 61,946
%N a(n) = indices n for which A138793(n) is prime.
%C Indices where number 1 occured in A138789.
%C There are no more primes for n<=5000.
%C a(3) > 20000. - _Robert Price_, Mar 24 2015
%e a(1) = 61 because the number 160695...654321 is prime.
%t b = {}; a = {}; Do[w = RealDigits[n]; w = First[w]; Do[AppendTo[a, w[[k]]], {k, 1, Length[w]}]; p = FromDigits[Reverse[a]]; If[PrimeQ[p], Print[n]; AppendTo[b, p]], {n, 1, 2000}]; b (* _Artur Jasinski_, Mar 30 2008 *)
%t Select[Range[1, 1000], PrimeQ[lst = {}; Do[lst = Join[lst, IntegerDigits[n]], {n, 1, #}]; FromDigits[Reverse[lst]]] &] (* _Robert Price_, Mar 24 2015 *)
%Y Cf. A000422, A116504, A007908, A116505, A138793, A138789.
%K nonn,bref,hard,more,base
%O 1,1
%A _Artur Jasinski_, Mar 30 2008, Mar 31 2008
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