login
Lower prime of a difference of 20 between consecutive primes.
15

%I #19 Apr 30 2024 05:43:30

%S 887,1637,3089,3413,3947,5717,5903,5987,6803,7649,8243,8543,8783,8867,

%T 9257,10223,10433,10667,11027,11093,11177,11447,11597,11657,11867,

%U 11987,13127,13421,13649,14087,14177,15473,16943,17519,17807

%N Lower prime of a difference of 20 between consecutive primes.

%H Remi Eismann, <a href="/A031938/b031938.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Pri#gaps">Index entries for primes, gaps between</a>

%F a(n) = prime(A320708(n)). - _R. J. Mathar_, Apr 30 2024

%e 887 is a term as the next prime is 907.

%t (*M6*) a=887; S={}; Do[b=NextPrime[a]; If[b-a==20,AppendTo[S,a]]; a=b,{10^4}]; S [_Zak Seidov_, Aug 14 2009]

%t Transpose[Select[Partition[Prime[Range[2000]], 2, 1], Last[#] - First[#] == 20 &]][[1]] (* _Bruno Berselli_, Apr 09 2013 *)

%o (Magma) [p: p in PrimesUpTo(20000) | NextPrime(p)-p eq 20]; // _Bruno Berselli_, Apr 09 2013

%K nonn

%O 1,1

%A _Jeff Burch_

%E Entries and b-file checked by _Zak Seidov_, Aug 14 2009