how to create a correlative, based on a start number (script field calculator)

Operativo_GISRTM_GIS

I try to create a script, which generates a correlative number (ID)
the start number can vary,
will not start from 1 or 0
it can be any number start  and the number of rows can also change

done this example but it didn't work

rec=0
def autoIncrement():
    global rec
    pStart = 11 #adjust start value, if req'd
    pInterval = 5 #adjust interval value, if req'd
    if (rec == 0):
        rec = pStart
    else:
        rec = rec + pInterval
    return rec

expression
autoIncrement(ID)

expected result------------

ID

11

12

13

14

15

(sorry my bad English)Thank

danretired

Just use the field calculator rather than running the script... or copy and edit it exactly