This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A038869 #37 May 04 2025 18:28:37 %S A038869 7,19,31,139,199,229,271,601,619,661,811,829,1279,1429,1609,2029,2089, %T A038869 2131,2311,2551,2791,3169,3331,3391,3529,3769,4051,4159,4231,4261, %U A038869 4339,4639,4801,5419,5479,5659,5851,6271,6301,6361,6691,6961,7561,7951,8539 %N A038869 Primes p such that both p-2 and 2p-1 are prime. %C A038869 Primes p such that A(2*p) - 3*A(p) = 3 (7, 31, 661, 811, 2551, ...) and primes p such that 7*A(p) - A(2*p) = 21 (19, 139, 619, 1429, ...), where A=A288814, are both subsequences of A038869. - _David James Sycamore_, Aug 07 2017 %H A038869 Harvey P. Dale, <a href="/A038869/b038869.txt">Table of n, a(n) for n = 1..10000</a> %t A038869 Transpose[Select[Partition[Prime[Range[1200]],2,1],#[[2]]-#[[1]]==2 && PrimeQ[2#[[2]]-1]&]][[2]] (* _Harvey P. Dale_, Jun 19 2014 *) %o A038869 (Magma) [n: n in [0..10000]|IsPrime(n) and IsPrime(n-2) and IsPrime(2*n-1)]; // _Vincenzo Librandi_, Dec 18 2010 %o A038869 (PARI) is(n)=n%6==1 && isprime(n-2) && isprime(n) && isprime(2*n-1) \\ _Charles R Greathouse IV_, Aug 09 2017 %Y A038869 Cf. A005382, A118071. %K A038869 nonn %O A038869 1,1 %A A038869 _Thomas Kellar_