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from wot littel yu giv us, me thank term n=7+6n
so term 19=7+19*6=7+114=121
but her hedline at top sorta look like it sae n=19 & impli it =109
no telling wot yu want
If yu had a REEL sequens that start at 13, with stepsize=6, & end at 109
it hav 17 terms, & sum =1,037