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A130101
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Primes prime(n) such that 10*prime(n)+prime(n+1) is not prime.
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0
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3, 5, 7, 11, 13, 17, 19, 23, 29, 37, 41, 43, 53, 59, 67, 71, 79, 89, 97, 101, 103, 107, 109, 113, 127, 137, 139, 149, 163, 167, 173, 179, 181, 191, 193, 197, 199, 223, 227, 229, 233, 239, 241, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| a(11)=41 because 41 is prime, the nextprime is 43 and 10*41+43=453, 453 = 3*151 is not prime,
a(12)=43 because 43 is prime, the nextprime is 47 and 10*43+47=477, 477 = 3^(2)*53 is not prime,
a(13)=53 because 53 is prime, the nextprime is 59 and 10*53+59=589, 589 = 19*31 is not prime, ...
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MAPLE
| ts_p5_02:=proc(n) local a, b, i, ans; ans := [ ]: for i from 1 to n do a := 10*ithprime(i)+ithprime(i+1): if (isprime(a)=false) then ans := [ op(ans), ithprime(i) ]: fi od; RETURN(ans) end: ts_p5_02(300);
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CROSSREFS
| Cf. A129900.
Sequence in context: A155058 A007703 A002556 * A130057 A120637 A064534
Adjacent sequences: A130098 A130099 A130100 * A130102 A130103 A130104
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KEYWORD
| nonn
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AUTHOR
| Jani Melik (jani_melik(AT)hotmail.com), Aug 01 2007
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