stack columns into multiple columns

[Urraco]

Hi everybody!

I have a huge list, over 600.000 rows
I would like to distribute the columns x1 and x2 in groups of 500 rows in order, exactly as in the example below ( in the example I put only 5 rows to simplify)
is it possible with a power query or formula?
Thank yery much!

Book1
	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T
1	x1	x2	a1	a2	b1	b2	c1	c2	d1	d2	e1	e2	f1	f2	g1	g2	h1	h2	i1	i2
2	1	1982	1	1982	6	1987	11	1992	16	1983	21	1997	26	2002	31	2007	36	2012	41	2017
3	2	1983	2	1983	7	1988	12	1993	17	1982	22	1998	27	2003	32	2008	37	2013	42	2018
4	3	1984	3	1984	8	1989	13	1994	18	1983	23	1999	28	2004	33	2009	38	2014	43	2019
5	4	1985	4	1985	9	1990	14	1995	19	1982	24	2000	29	2005	34	2010	39	2015	44	2020
6	5	1986	5	1986	10	1991	15	1996	20	1983	25	2001	30	2006	35	2011	40	2016	45	2021
7	6	1987	46	2022	51	2027	56	2032	61	2037	66	2042	71	2047	76	2052	81	2057	86	2062
8	7	1988	47	2023	52	2028	57	2033	62	2038	67	2043	72	2048	77	2053	82	2058	87	2063
9	8	1989	48	2024	53	2029	58	2034	63	2039	68	2044	73	2049	78	2054	83	2059	88	2064
10	9	1990	49	2025	54	2030	59	2035	64	2040	69	2045	74	2050	79	2055	84	2060	89	2065
11	10	1991	50	2026	55	2031	60	2036	65	2041	70	2046	75	2051	80	2056	85	2061	90	2066
12	11	1992	91	2067	96	2072
13	12	1993	92	2068
14	13	1994	93	2069
15	14	1995	94	2070
16	15	1996	95	2071
17	16	1997
18	17	1998
19	18	1999
20	19	2000
21	20	2001
22	21	2002
23	22	2003
24	23	2004
25	24	2005
26	25	2006
27	26	2007
28	27	2008
29	28	2009
30	29	2010
31	30	2011
32	31	2012
33	32	2013
34	33	2014
35	34	2015
36	35	2016
37	36	2017
38	37	2018
39	38	2019
40	39	2020
41	40	2021
42	41	2022
43	42	2023
44	43	2024
45	44	2025
46	45	2026
47	46	2027
48	47	2028
49	48	2029
50	49	2030
51	50	2031
52	51	2032
53	52	2033
54	53	2034
55	54	2035
56	55	2036
57	56	2037
58	57	2038
59	58	2039
60	59	2040
61	60	2041
62	61	2042
63	62	2043
64	63	2044
65	64	2045
66	65	2046
67	66	2047
68	67	2048
69	68	2049
70	69	2050
71	70	2051
72	71	2052
73	72	2053
74	73	2054
75	74	2055
76	75	2056
77	76	2057
78	77	2058
79	78	2059
80	79	2060
81	80	2061
82	81	2062
83	82	2063
84	83	2064
85	84	2065
86	85	2066
87	86	2067
88	87	2068
89	88	2069
90	89	2070
91	90	2071
92	91	2072
93	92	2073
94	93	2074
95	94	2075
96	95	2076
97	96	2077
98	97	2078
99	98	2079
100	99	2080
101	100	2081
102	101	2082
103	102	2083
104	103	2084
105	104	2085
106	105	2086
107	106	2087
108	107	2088
109	108	2089
110	109	2090
111	110	2091
112	111	2092
113	112	2093
114	113	2094
115	114	2095
116	115	2096
117	116	2097
118	117	2098
119	118	2099
120	119	2100
121	120	2101
Sheet1

 

[awoohaw]

Thank you!
I get this error

Book3
	A	B	C	D	E	F	G
2	1	1982	1	1982	#REF!	#REF!	#REF!
3	2	1983
4	3	1984
5	4	1985
6	5	1986
7	6	1987
8	7	1988
Sheet1

Cell Formulas
Range	Formula
C2:G2	C2	=INDEX( IF(ISODD(COLUMN(C2)), 1*($A$2:$A$600000),1*($B$2:$B$600000)), MOD((ROW(C2)-2),5)+1+ (INT((COLUMN(C2)-3)/2))*5+ INT((ROW(C2)-2)/5)*45,1)

What is is in Row1? I'm not sure if that makes a difference. But I do not see any REF errors in your formulas. Strange.