A319937 Unitary sociable numbers of order 10.

525150234, 527787366, 528544218, 553128198, 612951066, 675192294, 735821562, 982674438, 998151162, 998151174, 5251502340, 5277873660, 5285442180, 5531281980, 6129510660, 6751922940, 7358215620, 9826744380, 9981511620, 9981511740

Offset

1,1

Links

Table of n, a(n) for n=1..20.

J. O. M. Pedersen, Known Unitary Sociable Numbers of order different from four [Via Internet Archive Wayback-Machine]

Eric Weisstein's World of Mathematics, Unitary Sociable Numbers

J. O. M. Pedersen, Order 10 cycles

Prog

(PARI) f(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)) - n;
isok10(n) = iferr(f(f(f(f(f(f(f(f(f(f(n)))))))))) == n, E, 0);
isok5(n) = iferr(f(f(f(f(f(n))))) == n, E, 0);
isok2(n) = iferr(f(f(n)) == n, E, 0);
isok1(n) = iferr(f(n) == n, E, 0);
isok(n) = isok10(n) && !isok1(n) && !isok2(n) && !isok5(n);

Crossrefs

Cf. A063919 (sum of proper unitary divisors).

Cf. A002827 (unitary perfect), A063991 (unitary amicable).

Cf. A097024 (order 5), A319917 (order 6), A097030 (order 14).

Sequence in context: A203261 A207041 A339551 * A186092 A034617 A135977

Adjacent sequences: A319934 A319935 A319936 * A319938 A319939 A319940

Keyword

nonn,more

Author

Michel Marcus, Oct 02 2018

Status

approved