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A331000
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Unitary Ruth-Aaron numbers: numbers k such that A008475(k) = A008475(k+1).
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3
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5, 77, 714, 948, 2491, 2996, 3450, 4293, 5405, 6669, 9125, 10807, 13869, 14587, 16932, 17346, 19511, 19967, 23323, 26642, 27104, 31931, 33019, 37925, 41124, 43616, 48635, 52554, 55499, 58077, 58695, 79248, 80837, 86088, 89979, 95709, 98644, 99163, 108458, 117467
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OFFSET
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1,1
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COMMENTS
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A variation of Ruth-Aaron numbers with unitary prime-power divisors instead of prime divisors.
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LINKS
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EXAMPLE
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MATHEMATICA
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s[1] = 0; s[n_] := Plus @@ (Power @@@ FactorInteger[n]); seq = {}; s1 = 0; Do[s2 = s[n]; If[s1 == s2, AppendTo[seq, n - 1]]; s1 = s2, {n, 2, 10^5}]; seq
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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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