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A216893
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Fibonacci numbers whose sum of prime divisors equals two times a Fibonacci number.
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1
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2, 8, 21, 55, 377, 610, 17711, 121393, 832040, 5702887, 19740274219868223167
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OFFSET
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1,1
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COMMENTS
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Fibonacci number F such that sopf(F)= 2*F’ where F’ is a Fibonacci number and sopf(F) is the sum of the distinct primes dividing F (A008472).
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LINKS
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EXAMPLE
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121393 = F(26) = 233*521 is in the sequence because 233 + 521 = 2*377 = 2*F(14).
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MAPLE
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with(combinat, fibonacci):with(numtheory): for n from 1 to 300 do:x:=fibonacci(n):y:=factorset(x):n1:=nops(y): s:=sum('y[i] ', 'i'=1..n1): ii:=0:for m from 1 to n while(ii=0) do:if s =2*fibonacci(m) then ii:=1:printf(`%d, `, x): else fi:od:od:
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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STATUS
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approved
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