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A015806 Numbers k not congruent to 0 (mod 3) such that phi(k) + 4 | sigma(k). 0
175, 220, 350, 752, 3772, 4720, 5092, 15296, 80320, 269872, 632752, 807650, 1126672, 1304320, 4176896, 4386476, 20945920, 37030556, 1073463296, 17178755072, 34796530432, 85897707520, 274873450496 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(24) > 10^12. - Donovan Johnson, Feb 28 2012
LINKS
MATHEMATICA
Select[Range[100000],
Divisible[DivisorSigma[1, #], EulerPhi[#] + 4] && !
Divisible[#, 3] &] (* David Nacin, Feb 28 2012 *)
CROSSREFS
Sequence in context: A102538 A045145 A351720 * A109836 A332047 A186211
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset corrected and a(10)-a(23) from Donovan Johnson, Feb 28 2012
STATUS
approved

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Last modified March 29 06:15 EDT 2024. Contains 371265 sequences. (Running on oeis4.)