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G.f.: A(x) = Sum_{n>=0} x^n / Product_{k=1..n} (1-x^k)^(n-k+1).
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%I #11 Sep 21 2021 09:06:51

%S 1,1,2,4,9,20,46,106,247,578,1359,3204,7573,17930,42512,100902,239694,

%T 569768,1355083,3224124,7673612,18268414,43500301,103599089,246761629,

%U 587822094,1400398656,3336473471,7949650646,18942098721,45136103113,107555568419,256302098369

%N G.f.: A(x) = Sum_{n>=0} x^n / Product_{k=1..n} (1-x^k)^(n-k+1).

%H Vaclav Kotesovec, <a href="/A206119/b206119.txt">Table of n, a(n) for n = 0..400</a>

%F a(n) ~ c / r^n, where r = A347968 = 0.419600352598356478498775753566700025318089363120016078... is the root of the equation QPochhammer(r) = r and c = 0.21842597743526022597060618810878279... - _Vaclav Kotesovec_, Aug 21 2018

%e G.f.: A(x) = 1 + x + 2*x^2 + 4*x^3 + 9*x^4 + 20*x^5 + 46*x^6 + 106*x^7 +...

%e where

%e A(x) = 1 + x/(1-x) + x^2/((1-x)^2*(1-x^2)) + x^3/((1-x)^3*(1-x^2)^2*(1-x^3)) + x^4/((1-x)^4*(1-x^2)^3*(1-x^3)^2*(1-x^4)) +...

%o (PARI) {a(n)=polcoeff(sum(m=0,n,x^m/prod(k=1,m,(1-x^k +x*O(x^n))^(m-k+1))),n)}

%Y Cf. A067687.

%K nonn

%O 0,3

%A _Paul D. Hanna_, Feb 03 2012