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A060421 Numbers n such that the first n digits of the decimal expansion of Pi form a prime. 12
1, 2, 6, 38, 16208, 47577, 78073, 613373 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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, Sep 10 2002

The corresponding primes are in A005042. - Alexander R. Povolotsky, Dec 17 2007

LINKS

Table of n, a(n) for n=1..8.

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, Constant Primes

Eric Weisstein's World of Mathematics, Integer Sequence Primes

Eric Weisstein's World of Mathematics, Pi Digits

Eric Weisstein's World of Mathematics, Pi-Prime

EXAMPLE

3 is prime, so a(1) = 1; 31 is prime, so a(2) = 2; 314159 is prime, so a(3) = 6; ...

MATHEMATICA

Do[If[PrimeQ[FromDigits[RealDigits[N[Pi, n + 10], 10, n][[1]]]], Print[n]], {n, 1, 9016} ]

CROSSREFS

Cf. A005042, A007523, A047658.

Sequence in context: A005530 A072191 A118324 * A054970 A211348 A120492

Adjacent sequences:  A060418 A060419 A060420 * A060422 A060423 A060424

KEYWORD

hard,nonn,base

AUTHOR

Michel ten Voorde (seqfan(AT)tenvoorde.org), Apr 05 2001

EXTENSIONS

a(6) = 47577 from Eric W. Weisstein, Apr 01 2006

a(7) = 78073 from Eric W. Weisstein, Jul 13 2006

a(8) = 613373 from Adrian Bondrescu, May 29 2016

STATUS

approved

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Last modified March 24 21:49 EDT 2017. Contains 283998 sequences.