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Smallest integer x such that the number of integers y<x satisfying sigma(y)/y > sigma(x)/x is exactly n.
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%I #11 Jul 01 2019 07:56:16

%S 1,3,10,5,9,7,15,32,132,11,21,13,44,70,52,17,25,19,38,33,198,23,35,46,

%T 39,76,234,29,220,31,224,62,51,136,260,37,57,55,74,41,1170,43,196,82,

%U 69,47,10440,154,222,94,520,53,744,148,77,190,87,59,182,61,93

%N Smallest integer x such that the number of integers y<x satisfying sigma(y)/y > sigma(x)/x is exactly n.

%C Conjecture: a(n) exists for all n.

%H Amiram Eldar, <a href="/A247034/b247034.txt">Table of n, a(n) for n = 0..421</a>

%o (PARI) lista(nn) = {v = vector(nn, n, sigma(n)/n); vmore = vector(nn+1); for (n=1, nn, nb = sum(i=1, n, v[i] > v[n]); if (vmore[nb+1] == 0, vmore[nb+1] = n);); for (i=1, #vmore, if (!vmore[i], break, print1(vmore[i], ", ")));}

%Y Cf. A000203 (sigma), A004394 (superabundant), A017665 and A017666 (sigma(n)/n).

%Y Cf. A247015.

%K nonn

%O 0,2

%A _Michel Marcus_, Sep 10 2014