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%I #27 Nov 17 2022 16:44:09
%S 12285,605,55,779,1081,37,119957,73153,2927269,239,25329329,7230607,
%T 964119281,66445153,7613527,18431675687,328796066369,264003743,
%U 11298797322497,59592560831,949755039781,2759891672513
%N Least odd number m such that m*2^n is an amicable number, and -1 if no such number exists.
%C Similar to A358320 but restricted to amicable numbers.
%H Sergei Chernykh, <a href="https://sech.me/boinc/Amicable/">Amicable Numbers</a>.
%o (PARI) f(m) = if (m, sigma(m)-m, 0);
%o fpm(p, m) = (2*p-1)*sigma(m) - p*m;
%o a(n) = my(p=2^n); forstep(m=1, +oo, 2, my(x=fpm(p,m)); if ((x!=p*m) && (f(x) == p*m), return(m)));
%Y Cf. A001065, A002025, A259180, A262625, A358320.
%K nonn,more
%O 0,1
%A _Michel Marcus_, Nov 17 2022
%E a(12)-a(22) were calculated using Chernykh's database by _Amiram Eldar_, Nov 17 2022