|   | 1 |  initial version  | 
The appropriate object would be a "lazy power series".
One can define a LazyPowerSeriesRing in Sage,
but it does not seem very capable so far, and in particular
cannot compute $1 / (1 - x)$.
From the list of tickets whose summary contains "lazy", the most relevant are:
Many seem stalled but #27347 seems promising.
|   | 2 |  No.2 Revision  | 
The appropriate object would be a "lazy power series".
One can define a LazyPowerSeriesRing in Sage,
but it does not seem very capable so far, and in particular
cannot compute $1 / (1 - x)$.
From the list of tickets whose summary contains "lazy", the most relevant are:
Many seem stalled but #27347 seems promising.
Edit: With #27347 (now closed and hopefully making it into Sage 8.8.beta3), one can now do:
sage: from sage.rings.lazy_laurent_series_ring import LazyLaurentSeriesRing
sage: L = LazyLaurentSeriesRing(ZZ, 'x')
sage: x = L.gen()
sage: f = ~(1 - x)
sage: f
1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + ...
sage: f[800]
1
|   | 3 |  No.3 Revision  | 
The appropriate object would be a "lazy power series".
One can define a LazyPowerSeriesRing in Sage,
but it does not seem very capable so far, and in particular
cannot compute $1 / (1 - x)$.
From the list of tickets whose summary contains "lazy", the most relevant are:
Many seem stalled but #27347 seems promising.
Edit: With #27347 (now closed and hopefully making it into Sage 8.8.beta3), one can now do:
sage: from sage.rings.lazy_laurent_series_ring import LazyLaurentSeriesRing
sage: L = LazyLaurentSeriesRing(ZZ, 'x')
sage: x = L.gen()
sage: f = ~(1 - x)
sage: f
1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + ...
sage: f[800]
1
A related interesting package is ore_algebra, see
 Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.
 
                
                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.