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 A265913 #28 Feb 16 2025 08:33:28
%S A265913 -80561663527802406257321747,-11695495424911987900947041440697,
%T A265913 -261735233712444492786795215139587,
%U A265913 -686681472061569603985711525865543,-8467957012200178807169459266490129,-205501290141049152491380112020976837,4705942878159923138262416607648599521
%N A265913 Values of Ramanujan's tau function that are prime.
%C A265913 Here, negative integers whose absolute value is prime are considered prime.
%H A265913 Dana Jacobsen, <a href="/A265913/b265913.txt">Table of n, a(n) for n = 1..1000</a> (first 23 terms from Eric W. Weisstein)
%H A265913 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TauFunctionPrime.html">Tau Function Prime</a>.
%F A265913 a(n) = A000594(A135430(n)).
%e A265913 A135430(1) = 63001, and tau(63001) = -80561663527802406257321747, so a(1) = -80561663527802406257321747.
%o A265913 (PARI) for (x=0, 1000, n=(2*x+1)^2; a=ramanujantau(n); if(isprime(abs(a)), print1(a", "))) \\ _Dana Jacobsen_, Dec 30 2015
%o A265913 (Perl) use ntheory ":all"; for (0..1000) { my $n = (2*$_+1)**2; my $a = ramanujan_tau($n); say $a if is_prime(abs($a)); } # _Dana Jacobsen_, Dec 30 2015
%Y A265913 Cf. A135430 (values of n for which tau(n) is prime).
%Y A265913 Cf. A000594 (Ramanujan's tau function tau(n)).
%K A265913 sign
%O A265913 1,1
%A A265913 _Eric W. Weisstein_, Dec 18 2015