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A130101 Primes prime(n) such that 10*prime(n)+prime(n+1) is not prime. 0
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; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..57.

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, ...

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);

CROSSREFS

Cf. A129900.

Sequence in context: A155058 A007703 A002556 * A130057 A226181 A120637

Adjacent sequences:  A130098 A130099 A130100 * A130102 A130103 A130104

KEYWORD

nonn

AUTHOR

Jani Melik, Aug 01 2007

STATUS

approved

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Last modified October 17 21:37 EDT 2019. Contains 328134 sequences. (Running on oeis4.)