

A140173


Numbers k such that sigma(k) = phi(k)*(sum of the digits of k).


2



1, 6, 3720, 25080, 237000, 353430, 1201560, 1402440, 2104440, 2147040, 4140360, 22007160, 60035220, 104370420, 110095020, 136222020, 402500280, 2203551000, 2223003120, 8720021310, 35590401000, 110232105060, 116046010080, 212062116000, 440401221000, 2181301242120
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

This sequence is a subsequence of A020492. There is no further term up to 33*10^6. Is it true that 10 divides all multidigit terms of the sequence?


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..36 (calculated using data from Jud McCranie)


EXAMPLE

sigma(237000) = phi(237000)*(2+3+7+0+0+0).


CROSSREFS

Cf. A020492, A140174.
Sequence in context: A198653 A198660 A048542 * A158663 A110106 A024087
Adjacent sequences: A140170 A140171 A140172 * A140174 A140175 A140176


KEYWORD

base,nonn


AUTHOR

Farideh Firoozbakht, May 15 2008


EXTENSIONS

7 more terms Sean A. Irvine, Sep 23 2009
a(20)a(25) from Donovan Johnson, Mar 06 2012
a(26) from Amiram Eldar, Dec 04 2019, using data from Jud McCranie


STATUS

approved



