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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 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 A285180 Adjacent sequences:  A175903 A175904 A175905 * A175907 A175908 A175909 KEYWORD nonn AUTHOR Manuel Valdivia, Oct 12 2010 STATUS approved

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