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 A063731 Numbers k such that Sum_{j=1..k} sigma(j) divides Product_{j=1..k} sigma(j). 1

%I

%S 1,5,8,15,50,52,53,55,63,68,72,96,103,157,176,196,211,219,287,288,302,

%T 303,321,327,348,360,364,365,381,402,417,421,430,431,438,444,452,454,

%U 465,472,478,504,506,512,514,530,531,534,555,565,576,584,588,594,607

%N Numbers k such that Sum_{j=1..k} sigma(j) divides Product_{j=1..k} sigma(j).

%H Harry J. Smith, <a href="/A063731/b063731.txt">Table of n, a(n) for n = 1..1000</a>

%o (PARI) for(n=1,300,a=sum(k=1,n, sigma(k)); b=prod(k=1,n, sigma(k)); if(Mod(b,a)==0,print(n)))

%o (PARI) { n=0; a=0; b=1; for (m=1, 10^9, a+=sigma(m); b*=sigma(m); if (b%a==0, write("b063731.txt", n++, " ", m); if (n==1000, break)) ) } \\ _Harry J. Smith_, Aug 28 2009

%K easy,nonn

%O 1,2

%A _Jason Earls_, Aug 12 2001

%E More terms from _Matthew Conroy_, Aug 21 2001

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Last modified December 11 18:19 EST 2019. Contains 329925 sequences. (Running on oeis4.)