A049392 - OEIS

%I #13 Jan 16 2020 08:45:52

%S 1,-10,-75,-1000,-16250,-292500,-5606250,-112125000,-2312578125,

%T -48821093750,-1049653515625,-22901531250000,-505742148437500,

%U -11281940234375000,-253843655273437500,-5753789519531250000

%N Expansion of (1-25*x)^(2/5).

%H Iain Fox, <a href="/A049392/b049392.txt">Table of n, a(n) for n = 0..718</a>

%F G.f.: (1-25*x)^(2/5).

%F a(n) = (5^n/n!) * Product_{k=0..n-1} (5*k-2).

%F a(n) ~ -2/5*Gamma(3/5)^-1*n^(-7/5)*5^(2*n)*{1 + 7/25*n^-1 + ...}. - Joe Keane (jgk(AT)jgk.org), Nov 24 2001

%e (1-x)^(2/5) = 1 - 2/5*x - 3/25*x^2 - 8/125*x^3 - ...

%o (PARI) first(n) = x='x+O('x^n); Vec((1-25*x)^(2/5)) \\ _Iain Fox_, Aug 10 2018

%Y Cf. A049381.

%K sign,easy

%O 0,2

%A Joe Keane (jgk(AT)jgk.org)

%E Definition corrected by _Georg Fischer_, Jan 16 2020