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%I #19 Aug 02 2019 03:46:13
%S 1,6,24,28,120,496,672,4320,4680,8128,26208,30240,32760,174592,199584,
%T 293760,435708,523776,2142720,2178540,8910720,17428320,20427264,
%U 23569920,33550336,45532800,91963648,142990848,459818240,1379454720,1476304896,6039429120
%N Numbers n such that gcd(sigma(n), n) > gcd(sigma(m), m) for all m < n.
%C a(30) > 10^9.
%e a(2) = 6 because gcd(sigma(1), 1) = 1, gcd(sigma(2), 2) = 1, gcd(sigma(3), 3) = 1, gcd(sigma(4), 4) = 1, gcd(sigma(5), 5) = 1, and for n = 6, we have gcd(sigma(6), 6) = 6, which is greater than the five preceding.
%o (PARI) mgcdab(n) = { m = 0; for (i=1, n, g = gcd(sigma(i), i); if (g > m, m = g; print1(i, ", ");););}
%Y Cf. A009194.
%K nonn
%O 1,2
%A _Michel Marcus_, Sep 16 2012
%E a(30)-a(32) from _Donovan Johnson_, Sep 17 2012
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