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 A307822 #10 May 06 2025 09:34:26
%S A307822 0,1,8,87,871,8690,86940,869417,8694205,86941922,869419437,8694194033
%N A307822 The number of e-perfect numbers below 10^n.
%F A307822 Limit_{n->oo} a(n)/10^n = 0.00869419399... (A318645) is the density of e-perfect numbers.
%e A307822 Below 10^2 there is only one e-perfect number, A054979(1) = 36, thus a(2) = 1.
%t A307822 fun[p_, e_] := DivisorSum[e, p^# &]; esigma[1] = 1; esigma[n_] := Times @@ fun @@@ FactorInteger[n]; c = 0; k = 1; seq={}; Do[ While[ k < 10^n, If[ esigma[k]==2k, c++ ]; k ++]; AppendTo[seq, c], {n, 1, 5}]; seq
%Y A307822 Cf. A051377, A054979, A318645, A307821.
%K A307822 nonn,more
%O A307822 1,3
%A A307822 _Amiram Eldar_, Apr 30 2019
%E A307822 a(11)-a(12) from _Amiram Eldar_, May 06 2025