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A239546 Sum of the prime factors of n, where n runs through perfect numbers. 1
5, 9, 33, 129, 8193, 131073, 524289, 2147483649, 2305843009213693953, 618970019642690137449562113, 162259276829213363391578010288129, 170141183460469231731687303715884105729 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = A008472(A000396(n)). - Michel Marcus, Mar 21 2014
a(n) = A000668(n) + 2 (conjectured). - Michel Marcus, Mar 21 2014
EXAMPLE
First perfect number is 6, its two prime factors are 2 and 3, so a(1) = 5.
MATHEMATICA
(* based on the code of Harvey P. Dale in A000396 *)
perf=(# (#+1))/2&/@Select[2^Range[1000]-1, PrimeQ];
spf[n_]:=Total[First/@FactorInteger[n]]; spf/@perf (* Ivan N. Ianakiev, Jul 11 2015 *)
CROSSREFS
Sequence in context: A028351 A211952 A098640 * A083832 A070969 A200376
KEYWORD
nonn
AUTHOR
Madaline McCluskey, Mar 21 2014
EXTENSIONS
Typo in data corrected by Michel Marcus, Mar 21 2014
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)