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 A137291 #21 May 29 2025 15:47:44 %S A137291 1,2,3,4,6,8,10,12,14,15,18,20,24,27,28,31,32,34,40,43,47,48,51,52,55, %T A137291 62,65,68,72,82,86,87,91,94,99,100,104,107,111,119,123,128,129,130, %U A137291 132,133,134,135,139,141,150,152,170,172,177,180,182,191,200,202,209,211 %N A137291 Numbers m such that prime(m)^2-2 is prime. %C A137291 For m>=1, for these and only these numbers m, A242719(m) = prime(m)^2 + 1. Since A242719(m) >= prime(m)^2 + 1, then the equality is obtained on this and only this sequence. - _Vladimir Shevelev_, Sep 04 2014 %H A137291 Reinhard Zumkeller, <a href="/A137291/b137291.txt">Table of n, a(n) for n = 1..10000</a> %F A137291 A103960(a(n)) - A210481(a(n)) = 1. - _Reinhard Zumkeller_, Jul 30 2015 %F A137291 a(n) = A049084(A049002(n)). - _R. J. Mathar_, Apr 09 2008 %e A137291 prime(24)*prime(24)-2 = 89*89-2 = 7919 is prime, so n=24 belongs to the sequence. %t A137291 Select[Range[211],PrimeQ[Prime[#]^2-2]&] (* _James C. McMahon_, May 28 2025 *) %o A137291 (Haskell) %o A137291 a137291 n = a137291_list !! (n-1) %o A137291 a137291_list = filter ((== 1) . a010051' . a049001) [1..] %o A137291 -- _Reinhard Zumkeller_, Jul 30 2015 %o A137291 (PARI) is(n,p=prime(n))=isprime(p^2-2) \\ _Charles R Greathouse IV_, Feb 17 2017 %Y A137291 Cf. A000040, A062326, A242719, A242720, A246824, A010051, A049001, A103960, A210481. %K A137291 easy,nonn %O A137291 1,2 %A A137291 _Ctibor O. Zizka_, Apr 05 2008 %E A137291 More terms from _R. J. Mathar_, Apr 09 2008 %E A137291 Offset corrected by _Reinhard Zumkeller_, Jul 30 2015