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 A140515 Numbers n such that one of floor(10^n * Pi) or ceiling(10^n * Pi) is prime. 1
 0, 1, 5, 11, 18, 37, 601, 1901, 2394, 3970, 5826, 16207 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Carlos B. Rivera F. Puzzle 50. Approximation to pi with primes, The Prime Puzzles and Problems Connection. Eric Weisstein's World of Mathematics, Pi Digits EXAMPLE ceiling(10^11*Pi) = ceiling(314159265358.9...) = 314159265359 is prime, so 11 is in the sequence. MATHEMATICA 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 *) PROG (PARI) isA140515(n)=isprime(bitor(floor(10^n*Pi), 1)) CROSSREFS Sequence in context: A140697 A048253 A102174 * A056996 A102184 A290751 Adjacent sequences:  A140512 A140513 A140514 * A140516 A140517 A140518 KEYWORD nonn,base,more AUTHOR Marvin Ray Burns, Jul 01 2008, Jul 02 2008 STATUS approved

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Last modified September 20 16:50 EDT 2021. Contains 347586 sequences. (Running on oeis4.)