A266276 - OEIS

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A266276

a(n) = the smallest number k such that phi(k) = n*phi(k-1).

2, 3, 7, 1261, 11242771 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	LINKS	`Table of n, a(n) for n=1..5.`
	EXAMPLE	`a(3) = 7 because 7 is the smallest number k such that phi(k) = nphi(k-1); phi(7) = 6 =3phi(6) = 3*2.`
	PROG	`(MAGMA) a:=func<n\|exists(r){k:k in[2..10^8] \| EulerPhi(k) eq n*EulerPhi(k-1)}select r else 0>; [a(n):n in[1..5]]`
	CROSSREFS	`Sequences of numbers n such that phi(n) = kphi(n-1) for k = 1, 2, 3, 4, 5: {A001274 + 1} for k=1; A171271 = {A050472 + 1} for k=2; A266268 = {A067143 + 1} for k=3; A268126 = {A172314 + 1} for k=4; {A201253 + 1} for k=5.` `Cf. A000010 (phi(n)), A266269 (the smallest numbers k such that phi(k) >= nphi(k-1)).` `Sequence in context: A069503 A077524 A238400 * A088252 A320432 A196303` `Adjacent sequences: A266273 A266274 A266275 * A266277 A266278 A266279`
	KEYWORD	`nonn,more`
	AUTHOR	`Jaroslav Krizek, Jan 26 2016`
	STATUS	`approved`

Last modified October 14 16:48 EDT 2019. Contains 328022 sequences. (Running on oeis4.)