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 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 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

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Last modified November 30 15:52 EST 2021. Contains 349420 sequences. (Running on oeis4.)