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A015843 Numbers k such that phi(k) | sigma(k + 5). 6
1, 2, 6, 9, 10, 16, 18, 22, 28, 30, 33, 42, 64, 65, 71, 72, 82, 87, 90, 114, 130, 136, 156, 182, 198, 208, 215, 280, 294, 336, 380, 390, 403, 451, 616, 660, 683, 755, 777, 964, 990, 1168, 1260, 1267, 1330, 1342, 1348, 1480, 1638, 1744, 1953, 2025, 2074, 2088 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[3000], Divisible[DivisorSigma[1, 5 + #], EulerPhi[#]] &] (* David Nacin, Mar 03 2012 *)
PROG
(PARI) isok(n) = !(sigma(n+5) % eulerphi(n)); \\ Michel Marcus, Feb 05 2017
CROSSREFS
Sequence in context: A276937 A243373 A085304 * A109600 A370802 A370810
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(1) = 1 inserted by Ivan Neretin, Feb 05 2017
STATUS
approved

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Last modified May 26 02:43 EDT 2024. Contains 372807 sequences. (Running on oeis4.)