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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

Table of n, a(n) for n=1..12.

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

Cf. A000396, A008472.

Sequence in context: A028351 A211952 A098640 * A083832 A070969 A200376

Adjacent sequences:  A239543 A239544 A239545 * A239547 A239548 A239549

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 November 17 16:01 EST 2019. Contains 329236 sequences. (Running on oeis4.)