cp's OEIS Frontend

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.

A028873 Numbers k such that k^2 - 3 is prime.

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%I A028873 #42 Mar 02 2025 08:00:23
%S A028873 4,8,10,14,20,26,32,34,40,44,46,58,64,68,80,86,88,92,98,110,112,118,
%T A028873 124,128,136,140,142,146,164,172,190,194,202,206,208,218,220,250,254,
%U A028873 266,268,296,298,304,310,320,322,326,328,332,340,350,356,362,370,416,418
%N A028873 Numbers k such that k^2 - 3 is prime.
%H A028873 Nathaniel Johnston, <a href="/A028873/b028873.txt">Table of n, a(n) for n = 1..10000</a>
%H A028873 Patrick De Geest, <a href="https://www.worldofnumbers.com/consemor.htm">Palindromic Quasipronics of the form n(n+x)</a>.
%H A028873 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Near-SquarePrime.html">Near-Square Prime</a>.
%F A028873 a(n) = sqrt(A028874(n) + 3). - _Amiram Eldar_, Mar 01 2025
%e A028873 8^2 - 3 = 61 is prime, so 8 is in the sequence.
%t A028873 Select[Range[2, 500], PrimeQ[#^2 - 3] &] (* _Amiram Eldar_, Mar 01 2025 *)
%o A028873 (Magma) [n: n in [2..10000] |IsPrime(n^2-3)]; // _Vincenzo Librandi_, Aug 05 2010
%o A028873 (PARI) is(n)=isprime(n^2-3) \\ _Charles R Greathouse IV_, Jul 02 2013
%Y A028873 Cf. A028874.
%K A028873 nonn,easy
%O A028873 1,1
%A A028873 _Patrick De Geest_