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A335255
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Numbers k such that ab(k) + ab(k+1) + ab(k+2) = 0, where ab(k) is the abundance of k (A033880).
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0
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OFFSET
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1,1
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COMMENTS
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Equivalently, s(k) + s(k+1) + s(k+2) = k + (k+1) + (k+2), where s(k) is the sum of proper divisors of k (A001065).
a(4) > 10^11, if it exists.
a(4) > 10^13, if it exists. - Giovanni Resta, May 30 2020
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LINKS
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Table of n, a(n) for n=1..3.
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EXAMPLE
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5829840 is a term since ab(5829840) + ab(5829841) + ab(5829842) = 8428320 - 5513402 - 2914918 = 0.
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MATHEMATICA
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s[n_] := DivisorSigma[1, n] - n; Select[Range[6 * 10^6], s[#] + s[# + 1] + s[# + 2] == 3*# + 3 &]
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CROSSREFS
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Cf. A000203, A001065, A033880, A335254.
Sequence in context: A203931 A309835 A321365 * A250503 A268333 A203869
Adjacent sequences: A335252 A335253 A335254 * A335256 A335257 A335258
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KEYWORD
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nonn,hard,bref,more
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AUTHOR
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Amiram Eldar, May 28 2020
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STATUS
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approved
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