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A175906
Numbers n of the form 2^(A000043-1)*A046528 such that sigma(n) is a perfect number.
0
12, 10924032, 16125952, 3757637632, 45091651584, 66563866624, 727145809044307968, 1152771972099211264, 845044701535107443245558061611352064
OFFSET
1,1
COMMENTS
sigma(sigma(A046528(2,12,13,18,21,22,56,57,175,176,177,..))) is Mersenne prime.
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
KEYWORD
nonn
AUTHOR
Manuel Valdivia, Oct 12 2010
STATUS
approved