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A233563
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Numbers for which the number of prime divisors counted with multiplicity and the sum of the distinct prime divisors are both perfect.
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1
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1104, 1656, 2128, 2484, 3726, 4620, 6930, 7448, 11550, 12285, 12696, 16170, 19044, 20216, 20475, 23568, 25410, 26068, 28566, 28665, 34125, 35352, 47775, 53028, 53235, 54544, 66885, 70756, 71875, 79542, 88725, 91238, 124215, 146004, 190904, 192052, 201180
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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1104 is in the sequence because bigomega(1104) = 6 and sopf(1104) = 28,
23568 is in the sequence because bigomega(23568) = 6 and sopf(23568) = 496,
389904 is in the sequence because bigomega(389904) = 6 and sopf(389904) = 8128.
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MAPLE
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with(numtheory): lst:={6, 28, 496, 8128, 33550336, 8589869056, 137438691328, 2305843008139952128, 2658455991569831744654692615953842176, 191561942608236107294793378084303638130997321548169216} :n1:=nops(lst): for n from 1 to 1000000 do :x:=factorset(n):n2:=nops(x): s:=sum('x[i]', 'i'=1..n2):
ii:=0:for m from 1 to n1 do:if s=lst[m] then ii:=1:else fi:od:jj:=0:for p from 1 to n1 do:if bigomega(n)=lst[p] then jj:=1:else fi:od:if ii=1 and jj=1 then printf(`%d, `, n):else fi:od:
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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