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 A138935 #19 Sep 10 2024 16:14:26 %S A138935 3,7,10,11,12,13,24,28,47,48,49,56,57,88,90,92,108,110,116,120,127, %T A138935 134,141,149,161,181,198,202,206,236,248,288,357,384,420,458,500,530, %U A138935 536,619,620,694,798,897,929,981,992,1064,1134,1230,1670,1807,2094,2369 %N A138935 Indices k such that A019323(k)=Phi[k](5) is prime, where Phi is a cyclotomic polynomial. %C A138935 Can there be an odd multiple of 5 in this sequence? %H A138935 Robert Price, <a href="/A138935/b138935.txt">Table of n, a(n) for n = 1..110</a> %H A138935 Yves Gallot, <a href="http://yves.gallot.pagesperso-orange.fr/papers/cyclotomic.html">Cyclotomic polynomials and prime numbers</a> %H A138935 <a href="/index/Cy#CyclotomicPolynomialsValuesAtX">Index entries for cyclotomic polynomials, values at X</a> %t A138935 Select[Range[1000], PrimeQ[Cyclotomic[#, 5]] &] %o A138935 (PARI) for( i=1,999, ispseudoprime( polcyclo(i,5)) && print1( i",")) %Y A138935 Cf. A019323, A138920-A138940. %K A138935 nonn %O A138935 1,1 %A A138935 _M. F. Hasler_, Apr 03 2008 %E A138935 a(48)-a(54) from _Robert Price_, Apr 14 2012