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A222960 Numbers n such that 2*n + {3, 5, 9, 11} are all primes. 1
1, 4, 49, 94, 409, 739, 934, 1039, 1624, 1729, 2824, 4714, 6499, 7819, 7864, 8029, 9019, 9454, 9709, 10504, 11134, 12649, 15859, 17419, 21889, 25669, 27664, 31489, 33604, 34744, 36109, 38629, 39844, 40519, 41359, 44404 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

After 1, a(n) is congruent to 4 or 9 (mod 10), this means that a(n) is of the form 5k-1. Clearly, each term is not divisible by 3 and 11.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = (A007530(n)-3)/2. [Michael B. Porter, Mar 21 2013]

MATHEMATICA

Select[Range[50000], Union[PrimeQ[2 # + {3, 5, 9, 11}]]=={True}&]

PROG

(MAGMA) [n: n in [1..50000] | forall{2*n+k: k in [3, 5, 9, 11] | IsPrime(2*n+k)}];

CROSSREFS

Cf. A007530, A136162.

Sequence in context: A248558 A198384 A136196 * A061100 A147803 A112533

Adjacent sequences:  A222957 A222958 A222959 * A222961 A222962 A222963

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 13 2013

STATUS

approved

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Last modified March 23 14:17 EDT 2019. Contains 321431 sequences. (Running on oeis4.)