A047948 - OEIS

%I #34 Mar 13 2023 10:19:00

%S 47,151,167,251,257,367,557,587,601,647,727,941,971,1097,1117,1181,

%T 1217,1361,1741,1747,1901,2281,2411,2671,2897,2957,3301,3307,3631,

%U 3727,4007,4451,4591,4651,4987,5101,5107,5297,5381,5387,5557,5801,6067,6257,6311

%N Smallest of three consecutive primes with a difference of 6: primes p such that p+6 and p+12 are the next two primes.

%C Subsequence of A031924.

%H T. D. Noe, <a href="/A047948/b047948.txt">Table of n, a(n) for n=1..1000</a>

%F Let p(k) be the k-th prime; sequence gives p(n) such that p(n+2)-p(n+1)=p(n+1)-p(n)=6.

%e 47 is a term as the next two primes are 53 and 59.

%t ok[p_] := (q = NextPrime[p]) == p+6 && NextPrime[q] == q+6; Select[Prime /@ Range[1000], ok][[;; 45]] (* _Jean-François Alcover_, Jul 11 2011 *)

%t Transpose[Select[Partition[Prime[Range[1000]],3,1],Differences[#]=={6,6}&]] [[1]] (* _Harvey P. Dale_, Apr 25 2014 *)

%o (PARI) is_A047948(n)={nextprime(n+1)==n+6 && nextprime(n+7)==n+12 && isprime(n)} \\ _Charles R Greathouse IV_, Aug 17 2011, simplified by _M. F. Hasler_, Jan 13 2013

%o (PARI) p=2;q=3;forprime(r=5,1e4,if(r-p==12&&q-p==6,print1(p", "));p=q;q=r) \\ _Charles R Greathouse IV_, Aug 17 2011

%Y Cf. A031924, A078853, A046789.

%Y Cf. A033451 (four consecutive primes with difference 6)

%Y Cf. A001223, A033451, A052197, A052198.

%K easy,nonn

%O 1,1

%A _Enoch Haga_

%E Corrected by _T. D. Noe_, Mar 07 2008