Wavenumbers of cyclic ketones

Rank the compounds below in order of increasing C=O absorption frequency in IR spectrum (top - lowest wavenumber, bottom - highest wavenumber):
[![enter image description here](https://i.stack.imgur.com/D4oaO.png)](https://i.stack.imgur.com/D4oaO.png)


Question: Would I count compound #1's cyclopentane or all 11 carbons because wavenumber increases with 5C or smaller rings.


If I count #1 as a cyclopentane for this purpose then #3 has the lowest wavenumber and #2 has the highest.




Here is nice comparison of all 3 ring sizes. Octahydro-1H-inden-1-one (either *cis*- or *trans*-) carbonyl strechings fall between cyclohexanone and cyclobutanone, thus, fused ring is not a factor (it is to some extend because of sunstitution).


![IR image](https://i.stack.imgur.com/TnVe5.jpg)


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#1 Octahydro-1H-inden-1-one C=O stretch from [reference](http://actachemscand.org/pdf/acta_vol_17_p0738-0748.pdf) 


cis 1730 $\text{cm}^{-1}$  

[![enter image description here](https://i.stack.imgur.com/pZ1US.png)](https://i.stack.imgur.com/pZ1US.png)


trans 1754 $\text{cm}^{-1}$  

[![enter image description here](https://i.stack.imgur.com/HjkAp.png)](http://webbook.nist.gov/cgi/inchi?ID=C1191953&Mask=8)


#2 - Cyclobutanone [NIST Listing](http://webbook.nist.gov/cgi/inchi?ID=C1191953&Mask=8) C=O stretch at 1790 $\text{cm}^{-1}$ from [spectra](http://webbook.nist.gov/cgi/inchi?Scan=cob10190&Type=IR)


#3 - Cyclohexanone [NIST Listing](http://webbook.nist.gov/cgi/cbook.cgi?ID=C108941&Mask=4&Type=ANTOINE&Plot=on) C=O stretch at 1740 $\text{cm}^{-1}$ from [spectra](http://webbook.nist.gov/cgi/cbook.cgi?ID=C108941&Type=IR-SPEC&Index=0#IR-SPEC) 


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