

A072455


Count of all totients in the reduced residue system of 2n1.


1



1, 2, 3, 4, 4, 6, 7, 4, 8, 9, 7, 11, 10, 8, 13, 14, 9, 11, 16, 10, 17, 18, 9, 20, 19, 13, 22, 17, 15, 25, 26, 14, 21, 28, 16, 29, 30, 14, 23, 31, 19, 33, 27, 19, 35, 28, 22, 29, 37, 19, 38, 39, 16, 41, 42, 26, 44, 33, 26, 38, 41, 27, 36, 47, 29, 49, 43, 22, 51, 52, 32, 43, 40, 27
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..74.


FORMULA

a(n)=phi(n)A072454(n)=A000010(n)[A072451(n)1+A072453(n)]


EXAMPLE

n=31: reduced residue system[31]={1,...,30} with 15 odd and 15 even numbers. From odd ones only term=1 is totient, while from 15 even terms, 2 ones,{14,26},are nontotients so 13 ones are totients. All totients count 1+13=14, thus a([31+1]/2)=a(16)=14.


CROSSREFS

Cf. A000010, A037225, A072451A072457, A005277, A002202.
Sequence in context: A218443 A326035 A205787 * A177862 A066981 A130043
Adjacent sequences: A072452 A072453 A072454 * A072456 A072457 A072458


KEYWORD

nonn


AUTHOR

Labos Elemer, Jun 19 2002


STATUS

approved



