A381604 Least number k such that A381596(k) = n.
1, 2, 5, 10, 17, 116, 501, 512
Offset: 0
Examples
a(1) = 2 because P(2,z) = Sum_{i=1..2} A001223(i)*z^(i-1) = 1 + 2*z = 0 for z = -1/2.
a(2) = 5 because P(5,z) = Sum_{i=1..5} A001223(i)*z^(i-1) = 1 + 2*z + 2*z^2 + 4*z^3 + 2*z^4 = 0 for z = -1.6499348..., -0.5606729...
Programs
-
Maple
with(numtheory): for n from 0 to 20 do: ii:=0: for k from 1 to 10^3 while(ii=0) do : P:=add((ithprime(i+1)-ithprime(i))*x^(i-1),i=1..k): y:=fsolve(P,x,real):z:=evalf({%}):y:=nops(z): if y=n then ii:=1:printf (`%d %d \n`,n,k): else fi: od: od:
Comments