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Larger of the greatest cousin prime pair with n digits.
2

%I #25 Aug 22 2014 11:02:42

%S 7,83,971,9887,99881,999983,9999401,99999551,999999761,9999999707,

%T 99999999947,999999998867,9999999999083,99999999999467,

%U 999999999997841,9999999999997031,99999999999998717,999999999999999161,9999999999999996587,99999999999999999803

%N Larger of the greatest cousin prime pair with n digits.

%C The sum of the reciprocals converges to 0.156047....

%C It is only a (plausible) conjecture that this sequence is well-defined. See A152052. - _N. J. A. Sloane_, Aug 22 2014

%H Abhiram R Devesh, <a href="/A240170/b240170.txt">Table of n, a(n) for n = 1..100</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CousinPrimes.html">Cousin Primes</a>

%o (Python)

%o import sympy

%o for i in range(1,100):

%o ....a=(10**i)

%o ....p=sympy.prevprime(a)

%o ....while sympy.isprime(p-4)==False:

%o ........p=sympy.prevprime(p)

%o ....print(p)

%o (PARI)

%o a(n)=p=precprime(10^n);while(!isprime(p-4),p=precprime(p-1));return(p)

%o vector(50, n, a(n)) \\ _Derek Orr_, Aug 04 2014

%Y Cf. A046132, A152052, A240167.

%Y Analogous sequences with twin primes:

%Y - A092245 Lesser of the first twin prime pair with n digits.

%Y - A114429 Larger of the greatest twin prime pair with n digits.

%K nonn,base

%O 1,1

%A _Abhiram R Devesh_, Aug 02 2014