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 A084922 #20 Aug 24 2024 05:50:56 %S A084922 4,8,20,28,48,60,88,140,160,228,280,308,368,468,580,620,748,840,888, %T A084922 1040,1148,1320,1568,1700,1768,1908,1980,2128,2688,2860,3128,3220, %U A084922 3700,3800,4108,4428,4648,4988,5340,5460,6080,6208,6468,6600,7420 %N A084922 a(n) = (prime(n)-1)*(prime(n)+1)/6. %H A084922 Vincenzo Librandi, <a href="/A084922/b084922.txt">Table of n, a(n) for n = 3..840</a> %F A084922 a(n) = A084920(n)/6. %F A084922 a(n) = A084921(n)/3. %t A084922 Select[Range[0, 7000], PrimeQ[Sqrt[6 # + 1]]&] (* _Vincenzo Librandi_, Apr 11 2013 *) %t A084922 (Prime[Range[3,60]]^2 -1)/6 (* _G. C. Greubel_, May 02 2024 *) %o A084922 (Magma) [(p^2-1)/6: p in PrimesInInterval(4, 250)]; // _Vincenzo Librandi_, Apr 11 2013 %o A084922 (PARI) a(n) = (prime(n)^2-1)/6; \\ _Michel Marcus_, Mar 22 2016 %o A084922 (SageMath) [(n^2-1)//6 for n in prime_range(4,301)] # _G. C. Greubel_, May 02 2024 %Y A084922 Cf. A000040, A006093, A008864, A084920, A084921. %K A084922 nonn,easy %O A084922 3,1 %A A084922 _Reinhard Zumkeller_, Jun 11 2003