replace the first values in a sequence with zeros

Riny_van_Eekelen 

Thank you, that works perfectly in the example I provided.

However, ideally, I'd like these values as a series (or sequence/range?) instead of individual cell values. The reason for this is I need to be able to pick out every Nth value from the series using in this equation: 

=SUMPRODUCT(--(MOD(COLUMN($C1:C1)-COLUMN(C1),C3)=0),$C1:C1)

where C3 = the Nth value

and my original equation (except with zeros for the first values)

=IF(COLUMN(C1)-COLUMN($C1)+1>$C$2,OFFSET(C1,0,-$C$2+1),$C1):C1

would replace (COLUMN($C1:1)

(updated spreadsheet attached)

Each column is a month and I need this for a 10-year projection, so it would be possible to just have a data tab with your equation dynamically filling individual cells then reference them in the equation above, however, I'm hoping to have everything I need to be built into a single equation on a single tab.

Thank you for your help with this!