The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A319917 Unitary sociable numbers of order six. 4
 698130, 698310, 698490, 712710, 712890, 713070, 341354790, 348612390, 391662810, 406468314, 411838938, 519891750, 530946330, 582129630, 596171970, 621549630, 717175170, 740700270, 740700450, 743324934, 838902150, 919121658, 1009954170, 1343332998 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Note that the first 6 terms and the next 6 terms form two sociable groups. But then the next 12 terms belong to two distinct sociable groups. LINKS Table of n, a(n) for n=1..24. J. O. M. Pedersen, Known Unitary Sociable Numbers of order different from four [Via Internet Archive Wayback-Machine] J. O. M. Pedersen, Order 6 cycles, 2007. Eric Weisstein's World of Mathematics, Unitary Sociable Numbers PROG (PARI) f(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)) - n; isok6(n) = iferr(f(f(f(f(f(f(n)))))) == n, E, 0); isok3(n) = iferr(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) = isok6(n) && !isok1(n) && !isok2(n) && !isok3(n); (PARI) A063919(n) = my(f = factor(n)); prod(i = 1, #f~, f[i, 1]^f[i, 2] + 1) - n is(n) = my(c = n); for(i = 1, 5, c = A063919(c); if(c == 1 || c == n, return(0))); c = A063919(c); c == n \\ David A. Corneth, Oct 01 2018 CROSSREFS Cf. A063919 (sum of proper unitary divisors). Cf. A002827 (unitary perfect), A063991 (unitary amicable). Cf. A319902 (order 4), A097024 (order 5), A097030 (order 14). Sequence in context: A346358 A206518 A114676 * A205608 A205439 A027829 Adjacent sequences: A319914 A319915 A319916 * A319918 A319919 A319920 KEYWORD nonn AUTHOR Michel Marcus, Oct 01 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 29 00:22 EDT 2023. Contains 365739 sequences. (Running on oeis4.)