

A037159


Consider trajectory of n under iteration of map which send x to 3x  sigma(x) if this is >= 0 otherwise stops. Sequence gives values of n which eventually reach 0.


4



82, 120, 280, 672, 1464, 3048, 4964, 5568, 5688, 7666, 8969, 9176, 9288, 9514, 9616, 9706, 10132, 10186, 10232, 10478, 11496, 11884, 11914, 12232, 12320, 12820, 13248, 13842, 13854, 13866, 14848, 15076, 15098, 15196, 15364, 15586, 15892
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OFFSET

1,1


COMMENTS

A perfect number is a fixed point of this map.


LINKS

Table of n, a(n) for n=1..37.


EXAMPLE

82 > 120 > 0.


MATHEMATICA

max = 16000; f[0] = 0; f[n_ /; 0 < n < 9max] := 3n  DivisorSigma[1, n]; f[_] = 1; Select[ Range[max], FixedPoint[f, #] == 0 &] (* JeanFrançois Alcover, Feb 22 2012 *)


CROSSREFS

To see why 1, 16 and 23 are not in the sequence, see A058541, A058542 and A058545.
Cf. A033885, A033945, A033946, A037160.
Sequence in context: A296809 A223085 A260761 * A223088 A039547 A029704
Adjacent sequences: A037156 A037157 A037158 * A037160 A037161 A037162


KEYWORD

nonn,nice


AUTHOR

Naohiro Nomoto


EXTENSIONS

Better description from Jud McCranie, Dec 24 2000


STATUS

approved



