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A231232
Primes p = prime(k) such that p + 2*k is prime.
12
3, 5, 17, 23, 31, 37, 41, 43, 61, 89, 103, 107, 109, 113, 151, 163, 191, 193, 241, 251, 257, 269, 281, 307, 311, 313, 317, 359, 373, 409, 433, 463, 487, 557, 563, 593, 601, 607, 643, 647, 691, 701, 761, 787, 811, 823, 857, 863, 907, 911, 953, 977, 1019, 1033
OFFSET
1,1
LINKS
EXAMPLE
31 = prime(11) is a term: prime(11) + 2*11 = 31 + 22 = 53 is also prime.
89 = prime(24) is a term: prime(24) + 2*24 = 89 + 48 = 137 is also prime.
MAPLE
KD := proc() local a, b; a:= ithprime(n); b:= a+2*n; if isprime(b) then RETURN (a); fi; end: seq(KD(), n=1..500);
MATHEMATICA
t = Select[Table[{Prime[n], Prime[n] + 2*n}, {n, 200}], PrimeQ[#[[2]]] &]; Transpose[t][[1]] (* T. D. Noe, Nov 06 2013 *)
PROG
(PARI) is(n)=isprime(n+2*primepi(n)) && isprime(n) \\ Charles R Greathouse IV, Aug 25 2014
(Magma) [NthPrime(n): n in [1..250] | IsPrime(NthPrime(n)+2*n)]; // Vincenzo Librandi, Jan 19 2015
CROSSREFS
Cf. A061068 (primes: prime(m) plus its subscript).
Cf. A064402 (numbers n: prime(n)+n is prime).
Subsequence of A364877.
Sequence in context: A079017 A211440 A100564 * A154608 A024862 A025106
KEYWORD
nonn,easy
AUTHOR
K. D. Bajpai, Nov 06 2013
EXTENSIONS
Name edited by David A. Corneth, Sep 07 2023
STATUS
approved