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 A340731 #18 Feb 06 2021 21:51:59 %S A340731 10,15,25,27,29,31,33,36,37,44,54,64,69,78,81,82,88,102,106,110,121, %T A340731 142,148,177,183,192,211,212,240,270,272,274,280,314,332,337,338,344, %U A340731 367,381,384,404,412,421,429,434,460,463,467,490,502,511,519,523,530,551,559,584,586,588,614,624,628 %N A340731 Numbers k such that A067439(k) is prime. %H A340731 Robert Israel, <a href="/A340731/b340731.txt">Table of n, a(n) for n = 1..10000</a> %e A340731 a(3) = 25 is a term because A067439(25) = 83 is prime. %p A340731 filter:= proc(n) local t,k; %p A340731 isprime(add(`if`(igcd(n,k)=1, n mod k, 0),k=2..n-1)) %p A340731 end proc: %p A340731 select(filter, [$1..1000]); %o A340731 (PARI) isok(n) = isprime(sum(i=1, n-1, if(gcd(n, i)==1, n%i))); \\ _Michel Marcus_, Jan 18 2021 %Y A340731 Cf. A067439, A340736. %K A340731 nonn %O A340731 1,1 %A A340731 _J. M. Bergot_ and _Robert Israel_, Jan 17 2021