0,3

Also: Truncation to the integer part of the inverse function of A165900 = x -> x^2-x-1 (strictly increasing for x > 1/2): a(n) = floor(g(n)), where g = A165900^{-1}.

A left inverse of A165900 on the positive integers: a(A165900(n)) = n for all n>0.

Table of n, a(n) for n=0..86.

a(n) = A000194(n+2) - [n=1], where [P]=1 if P is true, [P]=0 else.

(PARI) A238598(n)=ceil(sqrtint(4*n+8)/2)-(n==1)

Sequence in context: A029836 A004257 A276611 * A156684 A070564 A072358

Adjacent sequences: A238595 A238596 A238597 * A238599 A238600 A238601

nonn

M. F. Hasler, Mar 01 2014

approved