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A240170
Larger of the greatest cousin prime pair with n digits.
2
7, 83, 971, 9887, 99881, 999983, 9999401, 99999551, 999999761, 9999999707, 99999999947, 999999998867, 9999999999083, 99999999999467, 999999999997841, 9999999999997031, 99999999999998717, 999999999999999161, 9999999999999996587, 99999999999999999803
OFFSET
1,1
COMMENTS
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
LINKS
Eric Weisstein's World of Mathematics, Cousin Primes
PROG
(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
CROSSREFS
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.
Sequence in context: A370522 A099668 A348303 * A231259 A187649 A368853
KEYWORD
nonn,base
AUTHOR
Abhiram R Devesh, Aug 02 2014
STATUS
approved