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A215491 Smaller of regular amicable pair. 2
220, 2620, 5020, 10744, 17296, 63020, 66928, 67095, 69615, 100485, 122265, 142310, 171856, 176272, 185368, 196724, 308620, 356408, 437456, 503056, 522405, 600392, 609928, 624184, 635624, 643336, 667964, 726104, 898216, 947835, 998104, 1077890, 1154450 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

An amicable pair (M,N) = (gm,gn) pair with g = gcd(M,N) is called regular if m and n are squarefree, and gcd(g,m) = gcd(g,n) = 1. Otherwise it is called irregular.

LINKS

Michel Marcus, Table of n, a(n) for n = 1..5960 (terms < 10^12 from Pedersen's tables)

J. O. M. Pedersen, Type system of amicable pairs

J. O. M. Pedersen, Known Amicable Pairs

Wikipedia, Regular pairs

EXAMPLE

The first amicable pair (220, 284) is regular because gcd(220, 284) = 4 with 220 = 4 * (5*11) and 284 = 4 * (71). So 220 belongs to the sequence.

The second amicable pair (1184, 1210) is not regular because gcd(1184, 1210)=2 and 1184 = 2 * (2^4*37). So 1184 does not belong to the sequence.

CROSSREFS

Cf. A002025.

Sequence in context: A251322 A257353 A211820 * A258537 A027797 A055663

Adjacent sequences:  A215488 A215489 A215490 * A215492 A215493 A215494

KEYWORD

nonn

AUTHOR

Michel Marcus, Aug 13 2012

STATUS

approved

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Last modified July 23 20:56 EDT 2019. Contains 325265 sequences. (Running on oeis4.)