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A267076 Amicable numbers with property that both members of the amicable pair have the same sopfr (as defined in A001414). 2
98671027044178875, 110707233329488965, 116112602631024285, 138000805229957475, 347701424633005443, 373158429641554557, 581028000695478105, 650656605928265895, 1057340336068271871, 1192941584025936129, 1317952177931347245, 1597858331524012755 (list; graph; refs; listen; history; text; internal format)



Both members of the amicable pair with same sopfr are listed in the sequence but are not necessarily adjacent.

The terms shown have 17, 18 digits (7 terms) and 19 digits (four terms).

Comment from N. J. A. Sloane, Jun 07 2016: (Start)

Sergei Chernykh has conducted several searches for amicable pairs in the 18-digit range (here p and q are the largest prime factors):

1) All pairs of the form (m*p^k1, n*q^k2) where k1 > 1 _OR_ k2 > 1

2) All pairs of the form (m*p, n*q) where m < 2*10^11 _AND_ n < 2*10^11

3) Current exhaustive search has already found all pairs of the form (m*p^k1, n*q^k2) where p < 21818622 for any k1, q, k2

If we combine the results of these searches it is easy to see that the remaining undiscovered pairs can only have the form (m*p, n*q) where their largest prime factors are p > 21818622 and q < 10000000 (2*10^18 / 2*10^11), so they can't have the same sopfr.

This means that all 18-digit members of A267076 are already known. There are no new ones. (End)

Sergei Chernykh with BOINC completed the amicable pairs list with 20 digits.


Sven Simon, Table of n, a(n) for n = 1..22

Sergei Chernykh, Amicable pairs list


To illustrate that 347701424633005443 and 373158429641554557 belong to the sequence:

347701424633005443 = 3*7^3*11*13*19*37*41*59*131*10607, sopfr(n) = 10942.

373158429641554557 = 3*7^2*11*13*19*311*383*839*9349, sopfr(n) = 10942.


Cf. A001414, A063990, A091340, A259180.

Sequence in context: A257168 A104837 A008923 * A146088 A217592 A092697

Adjacent sequences:  A267073 A267074 A267075 * A267077 A267078 A267079




Sven Simon, Jan 10 2016


Entry revised by Michel Marcus and N. J. A. Sloane, Jan 23 2016



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Last modified November 24 03:28 EST 2020. Contains 338605 sequences. (Running on oeis4.)