A110196 - OEIS

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A110196

Numbers n such that k=2n is the least k such that phi(n+k)=2*phi(k).

1, 13, 23, 97, 113, 131, 199, 227, 491, 859, 929 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`No other n < 10^6. Note that all n>1 are primes.`
	MATHEMATICA	`Do[k=1; While[EulerPhi[n+k] != 2*EulerPhi[k], k++ ]; If[k==2n, Print[n]], {n, 5000}]`
	CROSSREFS	`Cf. A050473 (least k such that phi(n+k)=2phi(k)).` `Sequence in context: A155093 A147443 A131447 A111943 A039448 A089768` `Adjacent sequences: A110193 A110194 A110195 * A110197 A110198 A110199`
	KEYWORD	`nonn`
	AUTHOR	`T. D. Noe (noe(AT)sspectra.com), Jul 15 2005`

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Last modified February 17 23:43 EST 2012. Contains 206085 sequences.