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 A271440 #12 Feb 07 2025 19:08:39
%S A271440 2,7,56,743,30746,773527,49783736,1837403019,160181560802,
%T A271440 29532404308019,1666577516860962,360777399719461393,
%U A271440 45691067858241526814,3477439299142731351087,518913689466371066697746,147680787468230866751370317,43490064769447225534580532962
%N A271440 a(n) = sigma(prime(n)^n) - phi(prime(n)^n).
%H A271440 Harvey P. Dale, <a href="/A271440/b271440.txt">Table of n, a(n) for n = 1..303</a>
%F A271440 a(n) = (2*prime(n)^n-prime(n)^(n-1)-1) / (prime(n)-1).
%F A271440 a(n) = (prime(n)^(n+1)-prime(n)^(n-1)*(prime(n)-1)^2-1) / (prime(n)-1).
%F A271440 a(n) = A051612(A062457(n)) = A000203(A062457(n)) - A000010(A062457(n)).
%p A271440 with(numtheory): A271440:=n->sigma(ithprime(n)^n)-phi(ithprime(n)^n): seq(A271440(n), n=1..30);
%t A271440 Table[DivisorSigma[1, Prime[n]^n] - EulerPhi[Prime[n]^n], {n, 20}]
%t A271440 DivisorSigma[1,#]-EulerPhi[#]&/@Table[Prime[n]^n,{n,20}] (* _Harvey P. Dale_, Feb 07 2025 *)
%o A271440 (PARI) a(n) = sigma(prime(n)^n) - eulerphi(prime(n)^n); \\ _Altug Alkan_, Apr 08 2016
%Y A271440 Cf. A000010 (phi), A000040 (primes), A000203 (sigma), A051612, A062457.
%K A271440 nonn,easy
%O A271440 1,1
%A A271440 _Wesley Ivan Hurt_, Apr 07 2016