%I
%S 5,9,33,129,8193,131073,524289,2147483649,2305843009213693953,
%T 618970019642690137449562113,162259276829213363391578010288129,
%U 170141183460469231731687303715884105729
%N Sum of the prime factors of n, where n runs through perfect numbers.
%F a(n) = A008472(A000396(n)).  _Michel Marcus_, Mar 21 2014
%F a(n) = A000668(n) + 2 (conjectured).  _Michel Marcus_, Mar 21 2014
%e First perfect number is 6, its two prime factors are 2 and 3, so a(1) = 5.
%t (* based on the code of _Harvey P. Dale_ in A000396 *)
%t perf=(# (#+1))/2&/@Select[2^Range[1000]1,PrimeQ];
%t spf[n_]:=Total[First/@FactorInteger[n]];spf/@perf (* _Ivan N. Ianakiev_, Jul 11 2015 *)
%Y Cf. A000396, A008472.
%K nonn
%O 1,1
%A _Madaline McCluskey_, Mar 21 2014
%E Typo in data corrected by _Michel Marcus_, Mar 21 2014
