

A143973


Distances between multiples of 3 in A000010.


1



2, 4, 1, 4, 1, 2, 5, 1, 1, 3, 4, 1, 1, 1, 1, 3, 1, 2, 4, 3, 2, 2, 1, 4, 1, 1, 2, 2, 3, 2, 1, 1, 2, 1, 1, 1, 2, 3, 2, 4, 1, 2, 2, 2, 1, 1, 4, 1, 1, 3, 1, 2, 1, 2, 3, 2, 3, 2, 2, 1, 2, 1, 3, 1, 1, 4, 1, 3, 1, 2, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 5, 1, 2, 1
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OFFSET

1,1


COMMENTS

Inspired by the question: is n == 1 mod phi(n) for n composite?


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


FORMULA

a(1) = 2 since the first two numbers k such that 3  phi(k) are 7 and 9, and 9  7 = 2.


MATHEMATICA

Differences @ Position[EulerPhi[Range[200]], _?(Divisible[#, 3] &)] // Flatten (* Amiram Eldar, Feb 29 2020 *)


CROSSREFS

Cf. A000010, A008585, A066498.
Sequence in context: A128570 A157284 A194733 * A011167 A014176 A317690
Adjacent sequences: A143970 A143971 A143972 * A143974 A143975 A143976


KEYWORD

nonn


AUTHOR

J. Perry (johnandruth(AT)jrperry.orangehome.co.uk), Sep 06 2008


EXTENSIONS

Offset corrected and more terms added by Amiram Eldar, Feb 29 2020


STATUS

approved



