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A140515
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Numbers n such that one of floor(10^n * Pi) or ceiling(10^n * Pi) is prime.
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1
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0, 1, 5, 11, 18, 37, 601, 1901, 2394, 3970, 5826, 16207
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OFFSET
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1,3
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LINKS
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Eric Weisstein's World of Mathematics, Pi Digits
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EXAMPLE
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ceiling(10^11*Pi) = ceiling(314159265358.9...) = 314159265359 is prime, so 11 is in the sequence.
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MATHEMATICA
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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 *)
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PROG
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(PARI) isA140515(n)=isprime(bitor(floor(10^n*Pi), 1))
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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STATUS
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approved
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