

A065987


Numbers n such that the first n binary digits of Pi expressed in decimal forms a prime.


4



2, 23, 31, 35, 124, 323, 2787, 5717, 6506, 8980, 106817
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..11.


EXAMPLE

The first 23 binary digits of Pi (A004601) are 11001001000011111101101 = 6588397 in decimal, which is a prime.


MATHEMATICA

Do[ If[ PrimeQ[ FromDigits[ First[ RealDigits[Pi, 2, n]], 2]], Print[n]], {n, 1, 7000} ]


CROSSREFS

Cf. A004601, A117721 (the primes themselves).
Sequence in context: A090150 A106102 A053232 * A107153 A049544 A049568
Adjacent sequences: A065984 A065985 A065986 * A065988 A065989 A065990


KEYWORD

base,nonn


AUTHOR

Robert G. Wilson v, Dec 10 2001


EXTENSIONS

8980 from Hans Havermann, Jul 23 2006
106817 from Hans Havermann, Sep 06 2006


STATUS

approved



