%I A090871
%S A090871 589407,2372675,5609052,5698663,12353466,12534100,14155932,24208353,
%T A090871 25303609,24208353,25303609
%N A090871 Numbers n such that the six numbers 1*prime(n)*prime(n+1), prime(n)*1*prime(n+1), 
               prime(n)*prime(n+1)*1, 1*prime(n-1)*prime(n), prime(n-1)*1*prime(n) 
               and prime(n-1)*prime(n)*1 are primes.
%e A090871 a(4)=5698663 because prime(5698662)=98842171, prime(5698663)=98842223 
               and
%e A090871 prime(5698664)=98842231 and the six numbers:
%e A090871 19884217198842223, 98842171198842223, 98842171988422231,
%e A090871 19884222398842231, 98842223198842231 and 98842223988422311
%e A090871 are primes.
%t A090871 v={}; Do[If[PrimeQ[FromDigits[Join[{1}, IntegerDigits[Prime[k-1]], IntegerDigits 
               [Prime[k]]]]]&&PrimeQ[FromDigits[Join[IntegerDigits[Prime[k-1]], 
               {1}, IntegerDigits[Prime[k]]]]]&&PrimeQ[FromDigits[Join[IntegerDigits 
               [Prime[k-1]], IntegerDigits[Prime[k]], {1}]]]&& PrimeQ[FromDigits 
               [Join[{1}, IntegerDigits[Prime[k]], IntegerDigits[Prime[k+1]]]]] 
               &&PrimeQ[FromDigits[Join[IntegerDigits[Prime[k]], {1}, IntegerDigits[ 
               Prime[k+1]]]]]&& PrimeQ[FromDigits[Join[IntegerDigits[Prime[k]], 
               IntegerDigits[Prime[k+1]], {1}]]], v=Append[v, k]; Print[v]], {k, 
               2, 3*10^7}]; v
%Y A090871 Sequence in context: A050518 A104962 A100386 this_sequence A151435 A022257 
               A106779
%Y A090871 Adjacent sequences: A090868 A090869 A090870 this_sequence A090872 A090873 
               A090874
%K A090871 more,nonn
%O A090871 1,1
%A A090871 Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jan 25 2004