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A171259 Numbers n such that sigma(n) = 14*phi(n) (where sigma=A000203, phi=A000010). 5
420, 2730, 5940, 12540, 24024, 38610, 48360, 66528, 77490, 81510, 133920, 140448, 141372, 156420, 163590, 282720, 284580, 298452, 348348, 498420, 600780, 681912, 701220, 771420, 792480, 901530, 918918, 1016730, 1052220, 1150968, 1372680, 1439592, 1654620 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

Kevin A. Broughan and Daniel Delbourgo, On the Ratio of the Sum of Divisors and Euler’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.

PROG

(PARI) for(k=1, 2e6, sigma(k) - 14*eulerphi(k) | print1(k", "));

CROSSREFS

Cf. A062699, A068391, A068390, A136547, A104900, A136540, A104901, A163667, A171256, A171257, A104902, A171258, A171260, A104903.

Sequence in context: A250383 A145678 A160372 * A061125 A269016 A317983

Adjacent sequences:  A171256 A171257 A171258 * A171260 A171261 A171262

KEYWORD

nonn

AUTHOR

Farideh Firoozbakht and M. F. Hasler, Mar 19 2010

STATUS

approved

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Last modified March 18 17:51 EDT 2019. Contains 321292 sequences. (Running on oeis4.)