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A240170
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Larger of the greatest cousin prime pair with n digits.
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2
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7, 83, 971, 9887, 99881, 999983, 9999401, 99999551, 999999761, 9999999707, 99999999947, 999999998867, 9999999999083, 99999999999467, 999999999997841, 9999999999997031, 99999999999998717, 999999999999999161, 9999999999999996587, 99999999999999999803
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OFFSET
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1,1
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COMMENTS
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The sum of the reciprocals converges to 0.156047....
It is only a (plausible) conjecture that this sequence is well-defined. See A152052. - N. J. A. Sloane, Aug 22 2014
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LINKS
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PROG
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(Python)
import sympy
for i in range(1, 100):
....a=(10**i)
....p=sympy.prevprime(a)
....while sympy.isprime(p-4)==False:
........p=sympy.prevprime(p)
....print(p)
(PARI)
a(n)=p=precprime(10^n); while(!isprime(p-4), p=precprime(p-1)); return(p)
vector(50, n, a(n)) \\ Derek Orr, Aug 04 2014
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CROSSREFS
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Analogous sequences with twin primes:
- A092245 Lesser of the first twin prime pair with n digits.
- A114429 Larger of the greatest twin prime pair with n digits.
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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