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 A023308 Primes that remain prime through 4 iterations of the function f(x) = 3x + 4. 2
 3203, 21683, 34613, 52813, 103843, 116933, 117443, 165443, 172933, 193603, 195053, 213973, 226783, 321053, 322193, 357613, 360323, 362233, 363403, 368743, 472393, 474143, 496333, 518543, 528673, 569083, 571303, 631853, 654623, 714893, 758503 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes p such that 3*p+4, 9*p+16, 27*p+52 and 81*p+160 are also primes. - Vincenzo Librandi, Aug 04 2010 All a(n) == 33 or 53 (mod 70). - John Cerkan, Oct 04 2016 LINKS John Cerkan, Table of n, a(n) for n = 1..10000 MAPLE select(n->isprime(n) and isprime(3*n+4) and isprime(9*n+16) and isprime(27*n+52) and isprime(81*n+160), [\$1..760000]); # Muniru A Asiru, Dec 07 2018 MATHEMATICA Select[Prime[Range[10000]], Union[PrimeQ[NestList[(3# + 4 &), #, 4]]] == {True} &] (* Alonso del Arte, Nov 30 2018 *) PROG (Magma) [n: n in [1..1000000] | IsPrime(n) and IsPrime(3*n+4) and IsPrime(9*n+16) and IsPrime(27*n+52) and IsPrime(81*n+160)] // Vincenzo Librandi, Aug 04 2010 (PARI) is(n) = my(x=3*n+4, i=0); while(1, if(!ispseudoprime(x), return(0), i++); if(i==4, return(1)); x=3*x+4) forprime(p=1, 760000, if(is(p), print1(p, ", "))) \\ Felix Fröhlich, Dec 07 2018 (GAP) Filtered([1..760000], n->IsPrime(n) and IsPrime(3*n+4) and IsPrime(9*n+16) and IsPrime(27*n+52) and IsPrime(81*n+160)); # Muniru A Asiru, Dec 07 2018 CROSSREFS Subsequence of A023209, A023247, A023278, and A034936. Sequence in context: A035777 A108001 A212074 * A171350 A251396 A054036 Adjacent sequences: A023305 A023306 A023307 * A023309 A023310 A023311 KEYWORD nonn AUTHOR David W. Wilson STATUS approved

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Last modified September 25 02:38 EDT 2023. Contains 365582 sequences. (Running on oeis4.)