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A063991 Unitary amicable numbers. 28
114, 126, 1140, 1260, 18018, 22302, 32130, 40446, 44772, 49308, 56430, 64530, 67158, 73962, 142310, 168730, 180180, 197340, 223020, 241110, 242730, 286500, 296010, 308220, 365700, 429750, 462330, 548550, 591030, 618570, 669900, 671580, 739620, 785148, 815100, 827652, 827700, 932100 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

C. A. Pickover, The Math Book, Sterling, NY, 2009; see p. 90.

LINKS

Michel Marcus, Table of n, a(n) for n = 1..149

R. M. Najar, The Unitary Amicable Pairs To 10^8

J. M. Pedersen, Known Unitary Amicable Pairs

J. O. M. Pedersen, Tables of Aliquot Cycles [Broken link]

J. O. M. Pedersen, Tables of Aliquot Cycles [Via Internet Archive Wayback-Machine]

J. O. M. Pedersen, Tables of Aliquot Cycles [Cached copy, pdf file only]

I. Peterson, Amicable Pairs, Divisors and a New Record

Eric Weisstein's World of Mathematics, Unitary Amicable Pair

PROG

(PARI) f(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)) - n;

isok1(n) = iferr(f(n) == n, E, 0);

isok2(n) = iferr(f(f(n)) == n, E, 0);

isok(n) = isok2(n) && !isok1(n); \\ Michel Marcus, Sep 29 2018

CROSSREFS

Union of A002952 and A002953.

Sequence in context: A057440 A113537 A127664 * A292020 A292019 A065118

Adjacent sequences:  A063988 A063989 A063990 * A063992 A063993 A063994

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Sep 18 2001

EXTENSIONS

More terms from Michel Marcus, Sep 29 2018

STATUS

approved

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Last modified December 5 18:49 EST 2019. Contains 329768 sequences. (Running on oeis4.)