SQL Server 2022

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-- Drop tbl if it exists, to avoid conflicts
DROP TABLE IF EXISTS tabl;

-- Create the tbl table
CREATE TABLE tbl (
    val INT
);

-- Insert values from 1 to 25
INSERT INTO tbl (val)
VALUES 
    (1), (2), (3), (4), (5), (6), (7), (8), (9), (10),
    (11), (12), (13), (14), (15), (16), (17), (18), (19), (20),
    (21), (22), (23), (24), (25);

-- Insert values from 50 to 110
INSERT INTO tbl (val)
VALUES 
    (60), (61), (62), (63), (64), (65), (66), (67), (68), (69), 
    (70), (71), (72), (73), (74), (75), (76), (77), (78), (79), 
    (80), (81), (82), (83), (84), (85), (86), (87), (88), (89), 
    (90), (91), (92), (93), (94), (95), (96), (97), (98), (99),
    (100), (101), (102), (103), (104), (105), (106), (107), (108), 
    (109), (110);
76 rows affected

SELECT top 1 val
FROM (
    SELECT 
        t1.row_num, 
        t1.val, 
        SUM(t2.val) - (t1.row_num * 50) AS total
    FROM (
        SELECT ROW_NUMBER() OVER (ORDER BY val) AS row_num, val
        FROM tbl
    ) t1
    JOIN (
        SELECT ROW_NUMBER() OVER (ORDER BY val) AS row_num, val
        FROM tbl
    ) t2 
    ON t1.row_num <= t2.row_num + 49 
       AND t2.row_num <= t1.row_num + 49 
       AND t2.row_num >= t1.row_num
    GROUP BY t1.row_num, t1.val
) a 
WHERE a.total = 1225;


val


--SELECT COUNT(*) FROM (

-- step 1 declare our sequence length
DECLARE @seq INT = 25;

-- step 2 self-join the val table to itself with join conditions that allow each row to match on a val that is equal to itself or the sum of itself and the seq length. If the number of rows in the resulting join for a specific start_val is the sequence legnth, then we can deduced that every possible spot where a number could be is filled, therefore the sequence must be complete.
with joined as (
SELECT distinct -- we need distinct here to make sure we don't get duplicates
  start.val start_val,
  seq.val seq_val
FROM tbl start 
  inner join tbl seq
  ON start.val + @seq > seq.val  -- upper bound is start_val + seq  
  and start.val <= seq.val  -- lower bound is start_val
),

-- step 3 aggregate the joined table, return only those start_values that had n number of record matches within the join condition window 
possible_starts as (
SELECT start_val, count(*) as sequence_length FROM joined
group by start_val
having count(*) = @seq
)

-- step 4 pull from the original table the lowest possible sequential list of ints   
SELECT tbl.* FROM tbl
WHERE val >= (SELECT MIN(start_val) from possible_starts)
AND val < (SELECT MIN(start_val) + @seq from possible_starts)

--)


val


1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25