A153135
Primes p such that 6*p - 7 is also prime.
Original entry on oeis.org
2, 3, 5, 11, 13, 19, 23, 29, 31, 41, 43, 53, 59, 61, 71, 73, 79, 83, 101, 109, 139, 149, 163, 173, 193, 199, 211, 229, 239, 241, 251, 263, 269, 271, 313, 331, 349, 353, 379, 401, 409, 431, 433, 449, 491, 503, 521, 563, 569, 613, 631, 643, 653, 659, 683, 691, 733, 743
Offset: 1
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[n: n in [0..900] | IsPrime(n) and IsPrime(6*n - 7)]; // "or" [p: p in PrimesUpTo(900) | IsPrime(6*p - 7)]; // Vincenzo Librandi, Oct 20 2012
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lst={};Do[p=Prime[n];If[PrimeQ[6*p-7],AppendTo[lst,p]],{n,6!}];lst (* Vladimir Joseph Stephan Orlovsky, Dec 23 2008 *)
Select[Prime[Range[110]],PrimeQ[6#-7]&] (* Harvey P. Dale, Oct 25 2011 *)
A153245
Numbers n>1 such that 6*n-7 is not prime.
Original entry on oeis.org
7, 12, 14, 17, 21, 22, 25, 27, 28, 32, 35, 36, 37, 38, 42, 47, 49, 51, 52, 55, 56, 57, 58, 62, 63, 64, 67, 69, 70, 72, 74, 77, 80, 82, 84, 87, 89, 90, 91, 92, 93, 97, 98, 102, 103, 105, 106, 107, 112, 113, 116, 117, 119, 120, 122, 123, 124, 126, 127, 129, 131, 132, 133
Offset: 1
Distribution of the terms in the following triangular array:
*;
*,*;
*,7,*;
*,*,*,*;
*,*,14,*,*;
*,12,*,*,25,*;
*, *,*,*,*, *,*;
*,*,21,*,*,38,*,*;
*,17,*,*,36,*,*,55,*;
*,*, *,*,*, *,*,*, *,*;
*,*,28,*,*,51,*,*,74,*,*;
*,22,*,*,47,*,*,72,*,*,97,*; etc.
where * marks the non-integer values of (2*h*k + k + h + 4)/3 with h >= k >= 1. - _Vincenzo Librandi_, Jan 17 2013
A153319
Primes p such that 6*p-7 is not prime.
Original entry on oeis.org
7, 17, 37, 47, 67, 89, 97, 103, 107, 113, 127, 131, 137, 151, 157, 167, 179, 181, 191, 197, 223, 227, 233, 257, 277, 281, 283, 293, 307, 311, 317, 337, 347, 359, 367, 373, 383, 389, 397, 419, 421, 439, 443, 457, 461, 463, 467, 479, 487, 499, 509, 523, 541
Offset: 1
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lst={};Do[p=Prime[n];If[ !PrimeQ[6*p-7],AppendTo[lst,p]],{n,6!}];lst
Select[Prime[Range[100]],!PrimeQ[6#-7]&] (* Harvey P. Dale, Dec 13 2019 *)
Typo in definition fixed by
Zak Seidov, Nov 14 2011
Showing 1-3 of 3 results.
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