login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A239546 Sum of the prime factors of n, where n runs through perfect numbers. 1

%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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 9 23:02 EST 2019. Contains 329880 sequences. (Running on oeis4.)