How to filter out rows from a very long table

How can I filter out rows for a huge table? I have pasted bellow a representative sample from the table (I would prefer if this could be done using loops?):

21613	864.52	25	114.0714	-25.8369
21614	864.56	26	114.1197	-26.0363
21615	864.6	27	114.1688	-26.2351
21616	864.64	28	114.2188	-26.4335
21617	864.68	29	114.2697	-26.6313
21618	864.72	30	114.3215	-26.8284
21619	864.76	31	114.3742	-27.0249
21620	864.8	32	114.4279	-27.2206
21621	864.84	33	114.4826	-27.4155
21622	864.88	34	114.5381	-27.6096
21623	864.92	35	114.5943	-27.8027
21624	864.96	36	114.6513	-27.9949
21625	865.00	37  114.7092	-28.1861
21626	865.04	38	114.7681	-28.3762
21627	865.08	39	114.8279	-28.5653
21628	865.12	40	114.8886	-28.7532
21629	865.16	41	114.9503	-28.9399
21630	865.2	42	115.0128	-29.1254
21631	865.24	43	115.0763	-29.3097
21632	865.28	44	115.1406	-29.4926
21633	865.32	45	115.2058	-29.6742
21634	865.36	46	115.2719	-29.8544
21635	865.4	47	115.3387	-30.0332
21636	865.44	48	115.4065	-30.2106
21637	865.48	49	115.4751	-30.3866
21638	865.52	50	115.5445	-30.5611
21639	865.56	51	115.6146	-30.7339
21640	865.6	52	115.6854	-30.9052
21641	865.64	53	115.7568	-31.0749
21642	865.68	54	115.8288	-31.2429
21643	865.72	55	115.9013	-31.4091

%I want the code to say keep row 5, and row 10, and row 15, and row 20, ... and so on
%the table size is 31x5
%I want to have a new table with the resulted new filtered table

Answer 1

[Chunru]

a = [
    21613	864.52	25	114.0714	-25.8369
21614	864.56	26	114.1197	-26.0363
21615	864.6	27	114.1688	-26.2351
21616	864.64	28	114.2188	-26.4335
21617	864.68	29	114.2697	-26.6313
21618	864.72	30	114.3215	-26.8284
21619	864.76	31	114.3742	-27.0249
21620	864.8	32	114.4279	-27.2206
21621	864.84	33	114.4826	-27.4155
21622	864.88	34	114.5381	-27.6096
21623	864.92	35	114.5943	-27.8027
21624	864.96	36	114.6513	-27.9949
21625	865.00	37  114.7092	-28.1861
21626	865.04	38	114.7681	-28.3762
21627	865.08	39	114.8279	-28.5653
21628	865.12	40	114.8886	-28.7532
21629	865.16	41	114.9503	-28.9399
21630	865.2	42	115.0128	-29.1254
21631	865.24	43	115.0763	-29.3097
21632	865.28	44	115.1406	-29.4926
21633	865.32	45	115.2058	-29.6742
21634	865.36	46	115.2719	-29.8544
21635	865.4	47	115.3387	-30.0332
21636	865.44	48	115.4065	-30.2106
21637	865.48	49	115.4751	-30.3866
21638	865.52	50	115.5445	-30.5611
21639	865.56	51	115.6146	-30.7339
21640	865.6	52	115.6854	-30.9052
21641	865.64	53	115.7568	-31.0749
21642	865.68	54	115.8288	-31.2429
21643	865.72	55	115.9013	-31.4091];

whatyouwant = a(5:5:end, :)

whatyouwant = 6×5

1.0e+04 * 2.1617 0.0865 0.0029 0.0114 -0.0027 2.1622 0.0865 0.0034 0.0115 -0.0028 2.1627 0.0865 0.0039 0.0115 -0.0029 2.1632 0.0865 0.0044 0.0115 -0.0029 2.1637 0.0865 0.0049 0.0115 -0.0030 2.1642 0.0866 0.0054 0.0116 -0.0031

[Reem RA]

Thank you so much, simple and straight forward!