

A318781


A188999(m)/m for the integers m such that A188999(m) is divisible by m, where A188999 is the biunitary sigma function.


1



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

1,2


COMMENTS

10496266260480 is a term of A189000 and it is the smallest known value x such that A188999(x)/x is 5.


LINKS

Table of n, a(n) for n=1..42.


FORMULA

a(n) = A188999(A189000(n))/A189000(n).


PROG

(PARI) a188999(n) = my(f = factor(n)); for (i=1, #f~, p = f[i, 1]; e = f[i, 2]; f[i, 1] = if (e % 2, (p^(e+1)1)/(p1), (p^(e+1)1)/(p1) p^(e/2)); f[i, 2] = 1; ); factorback(f) \\ after Michel Marcus in A189000
is_a189000(n) = ! frac(a188999(n)/n) \\ after Michel Marcus in A189000
for(n=1, oo, if(is_a189000(n), print1(a188999(n)/n, ", "))) \\ Felix Fröhlich, Sep 03 2018


CROSSREFS

Cf. A188999 (biunitary sigma), A189000 (multiply perfect for biunitary sigma).
Cf. A054030 (analog for sigma), A007691 (multiply perfect for sigma).
Sequence in context: A074795 A069577 A282426 * A316844 A331245 A130239
Adjacent sequences: A318778 A318779 A318780 * A318782 A318783 A318784


KEYWORD

nonn,more


AUTHOR

Michel Marcus, Sep 03 2018, following a suggestion from Felix Fröhlich


EXTENSIONS

a(33)a(42) from Giovanni Resta, Sep 03 2018


STATUS

approved



