

A160255


The sum of all the entries in an n x n Cayley table for multiplication in Z_n.


0



0, 1, 6, 16, 40, 63, 126, 176, 270, 365, 550, 624, 936, 1099, 1350, 1664, 2176, 2349, 3078, 3280, 3948, 4631, 5566, 5712, 7000, 7813, 8748, 9520, 11368, 11475, 13950, 14592, 16236, 17969, 19390, 20304, 23976, 25327, 27222, 28400, 32800, 32949, 37926, 38896
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OFFSET

1,3


COMMENTS

If n is prime, then A_n= (n1)(n^2n)/2.
Thanks to David Miller.


LINKS

Table of n, a(n) for n=1..44.


FORMULA

a(n)= Sigma(i=1 to n1) (n*(gcd(n,i))/2)*((n/(gcd(n,i))1).


EXAMPLE

For n=4
. 0_1_2_3
.00 0 0 0
.10 1 2 3
.20 2 0 2
.30 3 2 1
Sum becomes 6+4+6 = 16


PROG

(PARI) a(n) = sum(i=1, n1, (n*(gcd(n, i))/2)*((n/(gcd(n, i))1))) \\ Michel Marcus, Jun 16 2013


CROSSREFS

Sequence in context: A130902 A300371 A009955 * A213667 A123205 A123607
Adjacent sequences: A160252 A160253 A160254 * A160256 A160257 A160258


KEYWORD

nonn


AUTHOR

David Byrne (david.roggeveen.byrne(AT)gmail.com), May 06 2009


EXTENSIONS

More terms from Carl Najafi, Sep 29 2011


STATUS

approved



