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 A281958 #6 Feb 03 2017 10:50:54 %S A281958 2,173,317,509,709,773,787,947,1307,1447,1579,1613,1627,1867,2347, %T A281958 2467,2693,3307,3413,3547,3803,3923,4007,4243,4567,4597,4723,4793, %U A281958 4813,4937,4973,5227,5261,5387,5483,5557,5653,5717,5827,5843,6277,6397,6547,6653,6793,6907 %N A281958 Primes p such that p^2 - 1 is not a totient number (A002202). %C A281958 Corresponding values of p^2 - 1 are 3, 29928, 100488, 259080, 502680, 597528, 619368, 896808, 1708248, ... %H A281958 Charles R Greathouse IV, <a href="/A281958/b281958.txt">Table of n, a(n) for n = 1..10000</a> %e A281958 Prime number 173 is a term because 173^2 - 1 = 29928 is not a totient number. %o A281958 (PARI) is(n) = isprime(n) && !istotient(n^2-1); %Y A281958 Cf. A000010, A002202, A007617, A084920. %K A281958 nonn %O A281958 1,1 %A A281958 _Altug Alkan_, Feb 03 2017