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%I #16 May 07 2021 17:40:03
%S 0,1,5,11,18,37,601,1901,2394,3970,5826,16207
%N Numbers n such that one of floor(10^n * Pi) or ceiling(10^n * Pi) is prime.
%H Carlos B. Rivera F. <a href="http://www.primepuzzles.net/puzzles/puzz_050.htm">Puzzle 50. Approximation to pi with primes</a>, The Prime Puzzles and Problems Connection.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PiDigits.html">Pi Digits</a>
%e ceiling(10^11*Pi) = ceiling(314159265358.9...) = 314159265359 is prime, so 11 is in the sequence.
%t npQ[n_]:=Module[{c=10^n Pi},Total[Boole[PrimeQ[{Floor[ c],Ceiling[ c]}]]] == 1]; Select[Range[0,4000],npQ] (* The program generates the first 10 terms of the sequence. To generate more, increase the Range constant, but the program may take a long time to run. *) (* _Harvey P. Dale_, May 07 2021 *)
%o (PARI) isA140515(n)=isprime(bitor(floor(10^n*Pi),1))
%K nonn,base,more
%O 1,3
%A _Marvin Ray Burns_, Jul 01 2008, Jul 02 2008
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