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A098988 Denominators in series expansion of log(Product_{m>=1} (1+q^m)). 7

%I #22 Aug 04 2023 15:12:10

%S 1,1,2,3,4,5,3,7,8,9,5,11,3,13,7,5,16,17,18,19,10,21,11,23,6,25,13,27,

%T 7,29,5,31,32,11,17,35,36,37,19,39,20,41,21,43,11,15,23,47,12,49,50,

%U 17,26,53,27,55,7,57,29,59,5,61,31,63,64,65,11,67,34,23,35,71,72,73,37,75,19,77,39,79,40,81,41,83,21

%N Denominators in series expansion of log(Product_{m>=1} (1+q^m)).

%H Antti Karttunen, <a href="/A098988/b098988.txt">Table of n, a(n) for n = 0..16384</a>

%F Denominators of Sum_{d|n} ((-1)^(d+1))/d. - _Ridouane Oudra_, Apr 28 2019

%F Denominators of coefficients in expansion of Sum_{k>=1} (-1)^(k+1) * x^k / (k * (1 - x^k)). - _Ilya Gutkovskiy_, Aug 04 2023

%e q + (1/2)*q^2 + (4/3)*q^3 + (1/4)*q^4 + (6/5)*q^5 + (2/3)*q^6 + (8/7)*q^7 + (1/8)*q^8 + (13/9)*q^9 + ...

%o (PARI) A098988(n) = if(0==n, 1, denominator(sumdiv(n,d, ((-1)^(d+1))/d))); \\ _Antti Karttunen_, May 06 2022

%Y Cf. A098987 (numerators), A353688 (n / a(n)).

%K nonn,frac

%O 0,3

%A _N. J. A. Sloane_, Oct 24 2004

%E Data section extended up to term a(84) by _Antti Karttunen_, May 06 2022

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Last modified March 28 11:59 EDT 2024. Contains 371254 sequences. (Running on oeis4.)