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A175906 Numbers n of the form 2^(A000043-1)*A046528 such that sigma(n) is perfect number. 0
12, 10924032, 16125952, 3757637632, 45091651584, 66563866624, 727145809044307968, 1152771972099211264, 845044701535107443245558061611352064 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

sigma(sigma(A046528(2,12,13,18,21,22,56,57,175,176,177,..))) is Mersenne prime.

LINKS

Table of n, a(n) for n=1..9.

FORMULA

a(n)= 2^( A000043(2,5,5,6,7,7,8,8,9,9,9,..)-1)*A046528(2,12,13,18,21,22,56,57,175,176,177,..).

EXAMPLE

45091651584=2^18*3*7*8191, sigma(45091651584)=137438691328 is perfect number.

CROSSREFS

Cf. A000396, A000203, A000668, A000043, A046528, A063103.

Sequence in context: A013862 A116233 A145745 * A144546 A165970 A081357

Adjacent sequences:  A175903 A175904 A175905 * A175907 A175908 A175909

KEYWORD

nonn

AUTHOR

Manuel Valdivia, Oct 12 2010

STATUS

approved

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Last modified November 21 11:17 EST 2014. Contains 249777 sequences.