OFFSET
1,3
FORMULA
Lim_{n->oo} a(n)/10^n = 0.00869419399... (A318645) is the density of e-perfect numbers.
EXAMPLE
Below 10^2 there is only one e-perfect number, A054979(1) = 36, thus a(2) = 1.
MATHEMATICA
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
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Apr 30 2019
STATUS
approved