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 A343151 #11 Apr 09 2021 09:51:01
%S A343151 1,3,4,7,8,11,19,23,25,27,36,43,47,50,64,71,107,131,163,167,179,211,
%T A343151 223,225,242,243,251,271,307,343,359,419,431,439,443,467,503,571,691,
%U A343151 751,800,811,827,839,863,900,907,947,967,971,991,1019,1031,1058,1063,1091,1103,1187,1279,1296,1331
%N A343151 Numbers k such that 1+A083266(k) is prime.
%C A343151 Numbers k such that the sum of divisors of k + the sum of totatives of k is prime.
%H A343151 Robert Israel, <a href="/A343151/b343151.txt">Table of n, a(n) for n = 1..10000</a>
%e A343151 a(4) = 7 is a term because 1+A083266(n) = 29 is prime.
%p A343151 f:= n -> numtheory:-sigma(n) + n*numtheory:-phi(n)/2: f(1):= 2:
%p A343151 select(t -> isprime(f(t)), [$1..2000]);
%t A343151 {1}~Join~Select[Range[1331], PrimeQ[DivisorSigma[1, #] + # EulerPhi[#]/2] &] (* _Michael De Vlieger_, Apr 07 2021 *)
%Y A343151 Cf. A083266, A343148. Includes A231847.
%K A343151 nonn
%O A343151 1,2
%A A343151 _J. M. Bergot_ and _Robert Israel_, Apr 07 2021