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 A366812 #14 Nov 30 2024 06:24:49
%S A366812 3,4,8,32,212,2312,30600,544880,9727992,223796952,6500793728,
%T A366812 200560490132,7461870828048,309238687200848,13161101219883792,
%U A366812 615548170519961184,33465582319854797280,1930276657976815787040,117814338226489513454272,7858321551223903311137992
%N A366812 The sum of the divisors of prime(n)#+1 where p# is the product of all the primes from 2 to p inclusive.
%H A366812 Amiram Eldar, <a href="/A366812/b366812.txt">Table of n, a(n) for n = 0..98</a>
%F A366812 a(n) = sigma(prime(n)#+1) = A000230(A006862(n)).
%e A366812 a(6) = 30600 because the divisors of 13#+1 = 30031 are {1, 59, 509, 30031}.
%p A366812 seq(numtheory[sigma](mul(ithprime(k), k=1..n)-1), n=0..30);
%t A366812 Map[DivisorSigma[1, #] &, 1 + FoldList[Times, 1, Prime@ Range@ 19] ] (* _Michael De Vlieger_, Oct 25 2023 *)
%Y A366812 Cf. A006862, A000230, A054988, A366809, A366811, A366757.
%K A366812 nonn
%O A366812 0,1
%A A366812 _Sean A. Irvine_, Oct 23 2023