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 A171257 Numbers n such that sigma(n) = 11*phi(n) (where sigma=A000203, phi=A000010). 5
 2580, 16770, 18630, 28896, 35970, 61404, 66024, 147576, 163944, 215124, 224010, 296184, 399126, 408672, 443394, 464340, 476010, 574308, 856086, 862752, 868428, 931224, 957348, 1004910, 1110186, 1496610, 1721720, 1723290, 1833348, 1971288, 2139852, 2234790 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 (calculated using data from Jud McCranie, terms 1..1000 from Donovan Johnson) Kevin A. Broughan and Daniel Delbourgo, On the Ratio of the Sum of Divisors and Eulerâ€™s Totient Function I, Journal of Integer Sequences, Vol. 16 (2013), Article 13.8.8. Kevin A. Broughan and Qizhi Zhou, On the Ratio of the Sum of Divisors and Euler's Totient Function II, Journal of Integer Sequences, Vol. 17 (2014), Article 14.9.2. MATHEMATICA Select[Range[10^6], DivisorSigma[1, #] == 11 * EulerPhi[#] &] (* Amiram Eldar, Dec 04 2019 *) PROG (PARI) for(k=1, 2e6, sigma(k) - 11*eulerphi(k) | print1(k", ")); CROSSREFS Cf. A062699, A068391, A068390, A136547, A104900, A136540, A104901, A163667, A171256, A104902, A171258, A171259, A171260, A104903. Sequence in context: A201510 A303400 A235094 * A252159 A252167 A252160 Adjacent sequences:  A171254 A171255 A171256 * A171258 A171259 A171260 KEYWORD nonn AUTHOR Farideh Firoozbakht and M. F. Hasler, Mar 19 2010 STATUS approved

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Last modified July 2 15:30 EDT 2022. Contains 355029 sequences. (Running on oeis4.)