A360054 - OEIS

%I #35 Jan 28 2023 12:23:15

%S 0,0,0,0,3,8,21,55,154,412,1088,2632,6532,15371,35218,79982,180061,

%T 402560,894404,1975742

%N Number of odd amicable pairs where the smaller term of the pair is less than 10^n.

%C The list starts with n=1.

%C Comparing with the numbers of even amicable pairs in A066873, up to 10^4, the proportion of odd amicable pairs is 0%; up to 10^5 it is 23% and up to 10^10 is 28.9%. Up to 10^15, it is 40.4% and up to 10^19 this percentage is 45.9%. It is possible that this trend holds true for more amicable pairs, and thus most amicable number pairs are odd.

%D Song Y. Yan, Perfect, Amicable and Sociable Numbers. A Computational Approach, World Scientific, 1996, pages 151 - 153.

%H Sergei Chernykh, <a href="http://sech.me/ap/">Amicable pairs list</a>

%H Zoltan Galantai, <a href="https://eltehu-my.sharepoint.com/:t:/g/personal/galantai_gtk_elte_hu/EV04AhLUewBAoFvqxSZblR8BuMe_SYQ9a-nJG2L-hkLzRQ?e=TzRGHX">Number of odd amicable pairs where the smaller term of the pair is less than 10^20</a>

%Y Cf. A066873, A259180, A262623, A262622, A262625, A005408.

%K nonn,more

%O 1,5

%A _Zoltan Galantai_, Jan 23 2023