yogi_Starting With Cell (row 6 and column of cell marked etctrfh) Compute Row By Row Sum Of Every Nth Column

Google Spreadsheet   Post  #2119

Yogi Anand, D.Eng, P.E.      ANAND Enterprises LLC -- Rochester Hills MI     www.energyefficientbuild.com.   Feb-18-2017

question by Daxter2500:

https://productforums.google.com/forum/?utm_medium=email&utm_source=best_answer_notification_button#!topic/docs/g3siKRNfJq8;context-place=forum/docs
How to create a locked formula that counts every three columns, even if adding new columns

Hello,

First time poster, long time lurker & learner. But I can't figure out...

1) How to add an array of cells (specifically one cell from every three columns: H3, K3, N3, Q3.... FC3 to infinite ideally).

2) How to lock the formula (or part of the formula) even when I add new three new columns every day (Indirect has only taken me so far, but I've learned from you that it can not be combined with an Array Formula).

Success: I've been able to get a locked 7-day total from every three columns. When I add 3 new columns everyday, I don't have to adjust the formula at all:

=SUM(INDIRECT("K3"),INDIRECT("N3"),INDIRECT("Q3"),INDIRECT("T3"),INDIRECT("W3"),INDIRECT("Z3"),INDIRECT("AC3"))

Problem: But I want to add up all of my column TOTALS (from today to the start of my project) by adding up H3 (locked) to every three cells (so far it goes to column FC3, but will grow by three every day).

Any solutions?