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 A059109 #27 Feb 19 2024 10:29:41 %S A059109 3,4,5,6,7,8,9,11,12,14,16,17,18,21,24,25,26,29,30,31,33,35,36,38,42, %T A059109 47,54,61,63,65,66,67,71,74,75,78,81,87,91,97,99,101,105,117,119,121, %U A059109 123,127,128,131,132,135,139,140,143,144,147,149,154,156,158,162,172 %N A059109 Numbers m such that m*phi(m)-1 is prime, where phi is the Euler function (A000010). %H A059109 Charles R Greathouse IV, <a href="/A059109/b059109.txt">Table of n, a(n) for n = 1..10000</a> %t A059109 Select[Range[200],PrimeQ[# EulerPhi[#]-1]&] (* _Harvey P. Dale_, Aug 23 2012 *) %o A059109 (PARI) is(n)=isprime(n*eulerphi(n)-1) \\ _Charles R Greathouse IV_, Feb 21 2013 %o A059109 (Magma) [n: n in [1..200] | IsPrime(n*EulerPhi(n)-1)]; // _Vincenzo Librandi_, Jul 31 2018 %Y A059109 Cf. A000010, A046078. %K A059109 nonn %O A059109 1,1 %A A059109 _Jud McCranie_, Jan 03 2001