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A240170 Larger of the greatest cousin prime pair with n digits.

%I A240170 #28 May 22 2025 10:21:37
%S A240170 7,83,971,9887,99881,999983,9999401,99999551,999999761,9999999707,
%T A240170 99999999947,999999998867,9999999999083,99999999999467,
%U A240170 999999999997841,9999999999997031,99999999999998717,999999999999999161,9999999999999996587,99999999999999999803
%N A240170 Larger of the greatest cousin prime pair with n digits.
%C A240170 The sum of the reciprocals converges to 0.156047....
%C A240170 It is only a (plausible) conjecture that this sequence is well-defined. See A152052. - _N. J. A. Sloane_, Aug 22 2014
%H A240170 Abhiram R Devesh, <a href="/A240170/b240170.txt">Table of n, a(n) for n = 1..100</a>
%H A240170 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CousinPrimes.html">Cousin Primes</a>
%o A240170 (Python)
%o A240170 import sympy
%o A240170 for i in range(1,100):
%o A240170     a=(10**i)
%o A240170     p=sympy.prevprime(a)
%o A240170     while sympy.isprime(p-4)==False:
%o A240170         p=sympy.prevprime(p)
%o A240170     print(p)
%o A240170 (PARI)
%o A240170 a(n)=p=precprime(10^n);while(!isprime(p-4),p=precprime(p-1));return(p)
%o A240170 vector(50, n, a(n)) \\ _Derek Orr_, Aug 04 2014
%Y A240170 Cf. A046132, A152052, A240167.
%Y A240170 Analogous sequences with twin primes:
%Y A240170 - A092245 Lesser of the first twin prime pair with n digits.
%Y A240170 - A114429 Larger of the greatest twin prime pair with n digits.
%K A240170 nonn,base
%O A240170 1,1
%A A240170 _Abhiram R Devesh_, Aug 02 2014