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A266276 a(n) = the smallest number k such that phi(k) = n*phi(k-1). 3
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) = n*phi(k-1); phi(7) = 6 =3*phi(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) = k*phi(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) >= n*phi(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

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