A320704 -id:A320704 - cp's OEIS frontend

A031930 Lower prime of a difference of 12 between consecutive primes.

199, 211, 467, 509, 619, 661, 797, 997, 1201, 1237, 1307, 1459, 1499, 1511, 1531, 1709, 1789, 1811, 1889, 2069, 2099, 2297, 2399, 2447, 2579, 2621, 2777, 2927, 3049, 3067, 3169, 3191, 3259, 3331, 3347, 3499, 3559, 3659, 3931, 3989

Offset: 1

Jeff Burch

nonn

Some of the terms of this sequence are primes that are separated from both their predecessor and successor primes by 12, e.g., 211, 1511, 4409, 4691, 7841, 9871, 11299, 11411, 11731.  See A053072. - Harvey P. Dale, Apr 07 2013
Conjecture: The sequence is infinite and for every n, a(n+1) < a(n)^(1+1/n). Namely a(n)^(1/n) is a strictly decreasing function of n (See comment lines of the sequence A248855). - Jahangeer Kholdi and Farideh Firoozbakht, Nov 29 2014
Aside from 2 and 3, all primes are congruent to 1, 5, 7, 11 mod 12. Thus the least significant duodecimal digit of any term in this sequence is 1, 5, 7 or B. - Alonso del Arte, Aug 19 2017

			199 is a term as the next prime is 199 + 12 = 211.
211 is also a term since the next prime is 211 + 12 = 223.
But 223 is not a term since the next prime is 227, and 223 + 12 = 235 = 5 * 47.

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Index entries for primes, gaps between

Cf. A053072, A248855, A031928.

[p: p in PrimesUpTo(4000) | NextPrime(p)-p eq 12]; // Bruno Berselli, Apr 09 2013

Transpose[Select[Partition[Prime[Range[600]], 2, 1], Last[#] - First[#] == 12 &]][[1]] (* Harvey P. Dale, Apr 07 2013 *)

is(n)=nextprime(n+1)==n+12 && isprime(n) \\ Charles R Greathouse IV, Jul 02 2013

a(n) = prime(A320704(n)). - R. J. Mathar, Apr 30 2024

cp's OEIS Frontend

A031930 Lower prime of a difference of 12 between consecutive primes.

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