|
%I #15 Mar 24 2023 16:12:45
%S 1,44,66,398,1582,2484
%N Numbers k such that the concatenation of the first k positive integers plus prime(k) is prime.
%C For n > 1, a(n) is even.
%C a(7) > 20239. - _J.W.L. (Jan) Eerland_, Mar 03 2023
%e 66 is in the sequence because 1.2.3...65.66 + prime(66) is prime.
%t n=1;Monitor[Parallelize[While[True,If[PrimeQ[Prime[n]+FromDigits[Join@@IntegerDigits/@Range[n]]],Print[n]];n++];n],n] (* _J.W.L. (Jan) Eerland_, Mar 03 2023 *)
%K nonn,base,more
%O 1,2
%A _Farideh Firoozbakht_, Feb 19 2004
%E Edited by _Charles R Greathouse IV_, Apr 29 2010
%E a(6) from _Max Alekseyev_, Jan 28 2012
|
