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A060421
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Numbers n such that the first n digits of the decimal expansion of pi form a prime.
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7
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OFFSET
| 1,2
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COMMENTS
| The Brown link states that in 2001 Ed. T. Prothro reported discovering that 16208 gives a probable prime and that Prothro verified that all values for 500 through 16207 digits of pi are composites. - Rick L. Shepherd (rshepherd2(AT)hotmail.com), Sep 10 2002
The corresponding primes are in A005042. - Alexander R. Povolotsky (pevnev(AT)juno.com), Dec 17 2007
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LINKS
| K. S. Brown, Primes in the Decimal Expansion of Pi [Broken link?]
K. S. Brown, Primes in the Decimal Expansion of Pi [Cached copy]
Prime Curios, 314159
Prime Curios, 31415...36307 (16208-digits)
Eric Weisstein's World of Mathematics, Integer Sequence Primes
Eric Weisstein's World of Mathematics, Pi-Prime
Eric Weisstein's World of Mathematics, Pi-Prime
Eric Weisstein's World of Mathematics, Integer Sequence Primes
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EXAMPLE
| 3 is prime, so a(1) = 3; 31 is prime, so a(2) = 31; 314159 is prime, so a(3) = 314159; ...
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MATHEMATICA
| Do[ If[ PrimeQ[ FromDigits[ RealDigits[ N[ P, n+10], 10, n] [ [1] ] ] ], Print[n] ], {n, 1, 9016} ]
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CROSSREFS
| Cf. A005042, A007523.
Sequence in context: A005530 A072191 A118324 * A054970 A120492 A028300
Adjacent sequences: A060418 A060419 A060420 * A060422 A060423 A060424
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KEYWORD
| hard,nonn,base
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AUTHOR
| Michel ten Voorde (seqfan(AT)tenvoorde.org) Apr 05 2001
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EXTENSIONS
| a(6) found by Eric Weisstein (eric(AT)weisstein.com), Apr 01 2006
a(7) = 78073 found by Eric Weisstein (eric(AT)weisstein.com), Jul 13 2006
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