Annuity notation in LaTeX

Question

How do you write this in LaTeX:

Answer 1

I suggest to google for "actuarial" symbols and, of course, "LaTeX". You will find lots of examples, e.g. Annuity or Angle Operation Symbol in LaTeX.

I solved that problem some years ago, if I only remembered the context. . .

Answer 2

In the thread Actuarial & Annuity notation in LaTeX from text.comp.tex, Donald Arseneau provided the following \annu command:

\def\annu#1{_{% 
  \vbox{\hrule height .2pt 
    \kern 1pt 
    \hbox{$\scriptstyle {#1}\kern 1pt$}% 
  }\kern-.05pt 
  \vrule width .2pt 
}}

with the additional comment:

Tweak ".2pt" and "1pt" for appearance.