Calculate count based on multiple groups of 7 number range in Oracle

None of the other answers solve the problem where there are gaps between groups (they just assume groups are contiguous). This will skip gaps and put the groupid into ranges of 7.

Oracle Setup:

create table data(amount, customer_number, groupid, seqf) as (
    select '1000+', 5555, 51, 2 from dual union all
    select '1000+', 5555, 52, 3 from dual union all
    select '1000+', 5555, 55, 4 from dual union all
    select '1000+', 5555, 56, 4 from dual union all
    select '1000+', 5555, 57, 4 from dual union all
    select '1000+', 5555, 60, 2 from dual union all
    select '1000+', 5555, 61, 4 from dual union all
    select '1000+', 5555, 65, 2 from dual union all
    select '1000+', 5555, 69, 2 from dual union all
    select '2000+', 6666, 55, 2 from dual );

Query 1:

This finds the groups:

SELECT amount,
       customer_number,
       groupid,
       groupid + 6 AS max_groupid
FROM   (
  SELECT d.*,
         MIN( groupid )
           OVER ( PARTITION BY amount, customer_number )
           AS min_groupid,
         MIN( groupid )
           OVER (
             PARTITION BY amount, customer_number
             ORDER BY groupid
             RANGE BETWEEN 7 FOLLOWING AND UNBOUNDED FOLLOWING
           )
           AS next_groupid
  FROM   data d
)
START WITH groupid = min_groupid
CONNECT BY PRIOR amount          = amount
AND        PRIOR customer_number = customer_number
AND        PRIOR next_groupid    = groupid

which outputs:

AMOUNT | CUSTOMER_NUMBER | GROUPID | MAX_GROUPID
:----- | --------------: | ------: | ----------:
1000+  |            5555 |      51 |          57
1000+  |            5555 |      60 |          66
1000+  |            5555 |      69 |          75
2000+  |            6666 |      55 |          61

Query 2:

This counts the groups:

SELECT amount,
       customer_number,
       COUNT(*)
FROM   (
  SELECT d.*,
         MIN( groupid )
           OVER ( PARTITION BY amount, customer_number )
           AS min_groupid,
         MIN( groupid )
           OVER (
             PARTITION BY amount, customer_number
             ORDER BY groupid
             RANGE BETWEEN 7 FOLLOWING AND UNBOUNDED FOLLOWING
           )
           AS next_groupid
  FROM   data d
)
START WITH groupid = min_groupid
CONNECT BY PRIOR amount          = amount
AND        PRIOR customer_number = customer_number
AND        PRIOR next_groupid    = groupid
GROUP BY amount, customer_number

which outputs:

AMOUNT | CUSTOMER_NUMBER | COUNT(*)
:----- | --------------: | -------:
1000+  |            5555 |        3
2000+  |            6666 |        1

db<>fiddle here