A351728 - OEIS

%I #45 Mar 23 2022 12:49:29

%S 2,61,83,433,677,2351,2399,2441,4397,4457,4673,6257,6367,6961,8263,

%T 8713,8761,20627,21391,21649,22721,22871,23227,23761,25111,25321,

%U 25589,25609,25741,25841,26597,26731,26981,27179,27271,27299,27367,27409,27481,27961,28559,29881,40609,40927,40933,42197

%N Primes p such that if q is the next prime, p+A004086(q) and q+A004086(p) are prime.

%C For each term p except 2, A013632(p) is divisible by 6.

%H Robert Israel, <a href="/A351728/b351728.txt">Table of n, a(n) for n = 1..10000</a>

%e a(3) = 83 is a term because it is prime, the next prime is 89, and 83+98 = 181 and 38+89 = 127 are both prime.

%p revdigs:= proc(n) local L,i; L:= convert(n,base,10);

%p   add(L[-i]*10^(i-1),i=1..nops(L))

%p end proc:

%p Primes:= select(isprime, [2,seq(i,i=3..10000,2)]):

%p RPrimes:= map(revdigs,Primes):

%p Primes[select(i -> isprime(Primes[i]+RPrimes[i+1]) and isprime(RPrimes[i]+Primes[i+1]), [$1..nops(Primes)-1])]:

%Y Cf. A004086, A013632.

%K nonn,base

%O 1,1

%A _J. M. Bergot_ and _Robert Israel_, Mar 20 2022