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A335252 Numbers k such that k and k+2 have the same unitary abundance (A129468). 2
12, 63, 117, 323, 442, 1073, 1323, 1517, 3869, 5427, 6497, 12317, 18419, 35657, 69647, 79919, 126869, 133787, 151979, 154007, 163332, 181427, 184619, 333797, 404471, 439097, 485237, 581129, 621497, 825497, 1410119, 2696807, 3077909, 3751619, 5145341, 6220607 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Are 12, 442 and 163332 the only even terms?
Are there any unitary abundant numbers (A034683) in this sequence?
No further even terms up to 10^13. - Giovanni Resta, May 30 2020
LINKS
EXAMPLE
12 is a term since 12 and 14 have the same unitary abundance: A129468(12) = usigma(12) - 2*12 = 20 - 24 = -4, and A129468(14) = usigma(14) - 2*14 = 24 - 28 = -4.
MATHEMATICA
usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); udef[n_] := 2*n - usigma[n]; Select[Range[10^5], udef[#] == udef[# + 2] &]
CROSSREFS
The unitary version of A330901.
Sequence in context: A196335 A349159 A092224 * A212509 A212249 A309372
KEYWORD
nonn
AUTHOR
Amiram Eldar, May 28 2020
STATUS
approved

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Last modified April 16 03:17 EDT 2024. Contains 371696 sequences. (Running on oeis4.)