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 A330429 Numbers k such that phi(k) = phi(k+9), where phi (A000010) is Euler's totient function. 1
 9, 15, 1005079920836, 13695542245376, 26160864154416, 27402841561095, 27599063056565, 110263115897935, 124632211478775, 127400054266476, 154090744843026, 205849483744896, 231019991767556, 339938754880725, 459718637643265, 632733228632505, 646552697065275, 683008674773416, 884965354448175 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(20) > 10^15. LINKS Table of n, a(n) for n=1..19. Kevin Ford, Solutions of phi(n)=phi(n+k) and sigma(n)=sigma(n+k), arXiv:2002.12155 [math.NT], 2020. S. W. Graham, J. J. Holt, and C. Pomerance, On the solutions to phi(n) = phi(n+k), Number Theory in Progress, K. Gyory, H. Iwaniec, and J. Urbanowicz, eds., vol. 2, de Gruyter, Berlin and New York, 1999, pp. 867-882. CROSSREFS Cf. A000010, A007015. Cf. A001274, A001494, A330251, A179186, A179187, A179188, A179189, A179202. Cf. A276503, A276504, A217139. Sequence in context: A100241 A078794 A093595 * A215418 A133816 A048752 Adjacent sequences: A330426 A330427 A330428 * A330430 A330431 A330432 KEYWORD nonn AUTHOR Giovanni Resta, Mar 01 2020 STATUS approved

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Last modified June 3 18:44 EDT 2023. Contains 363116 sequences. (Running on oeis4.)