

A173665


Primes formed by the initial digits of the decimal expansion of 1/Catalan's constant.


0




OFFSET

1,1


COMMENTS

Primes found in 1/ A006752.
a(5) = 109174406...792972361 has 109 digits,
a(6) = 109174406...955798301 has 271 digits,
a(7) = 109174406...813410233 has 319 digits,
a(8) = 109174406...519744361 has 1223 digits.


LINKS

Table of n, a(n) for n=1..4.


EXAMPLE

1/Catalan's constant = 1.09174406..., so a(1) = 109 ; a(2) = 1091.


MAPLE

Digits := 100; n0 := evalf(1/Catalan); for i from 1 to 100 do x := trunc(10^i*n0):
if isprime(x) then printf(`%d, `, x): fi: od:


PROG

(PARI) default(realprecision, 350); C=intnum(t=0, 1, atan(t)/t); for(k=1, default(realprecision), ispseudoprime(10^k\C) & print(10^k\C, " \\ digits: ", k+1)) \\ [M. F. Hasler, Nov 24]


CROSSREFS

Cf. A006752, A014538.
Sequence in context: A061699 A239720 A096214 * A059936 A232118 A201849
Adjacent sequences: A173662 A173663 A173664 * A173666 A173667 A173668


KEYWORD

nonn,base


AUTHOR

Michel Lagneau, Nov 24 2010


STATUS

approved



