Excel function 过滤发生阶跃变化的数组

Question

I am trying to filter an array to only include those values that are not within a set distance of a change in that array.

Here's my example:

The input array increases monotonically in steps. I want to zero out any of the input values from N rows above to N rows below any point where the value changes. Cell $B$2 holds this "window" value.

For example, cell A9 (value 11) is different from cell A8 (value 5), so I want to zero out values that come from any cells from A7 to A11 inclusive. That is from -N to +N relative the cell where the change occurs, where N=2.

I can achieve the required output with non-array functions, using intermediate calculation columns, but since I am processing a large number of columns it would save greatly on spreadsheet real-estate if I could construct a single array formula that operates on the range A4:A25, and uses cell B1 for the size of N. I am using the current Excel Beta, so I have access to LET and LAMBDA if needed.

I have tried various combinations, using SEQUENCE, but I run into the issue that LET (or indeed any array functions) seems to fail if they contain two SEQUENCE statements.

I am continuing to work on this, but if anyone wants to have a try, I would be most grateful!

UPDATE: This formula does the trick, but needs to be copied down:

=A4*IF(AVERAGE(OFFSET(A4,-($B$1+1),0,2*($B$1+1),1))<>A4,0,1)

Answer 1

So, while the suggestion of @JvdV was not exactly what I was after, a hat-tip to them for the idea of offsetting the whole column up and down, which led to this:

=LET(input,A4:A25,up,OFFSET(input,-1*(B1+1),0),down,OFFSET(input,B1,0),input*IF(IFERROR(up*down,0)>0,IF(up=down,1,0),1))