Does anything get done to the year_code values of 1314 and or 1213 in the third row?
From what you post it isn't even clear if you have any SAS data set, do you?
If you have a SAS data set and want to change only the first observation something like;
Data want;
set have;
if _n_=1 then do; /*<= this does the first row only*/
year_code=201280;
output; /* replace the value and then save to output*/
year_code=201310;
output; /* second value and then save to output*/
year_code=2013500;
output; /* third value and then save to output*/
end; /* the block of statements for the first record*/
else output; /* write other records unchanged*/
run;
If there is supposed to be some logic in how other values may be assigned you should state it.