Why is my index obtained from 'getenv' not the correct number?

I am running a Matlab code through a PBS Job Array. I need to run the same Matlab script 186 times. When I submit the job array I use the index J 1-186:1 and I use the function 'getenv' to insert this value into Matlab.

I ran a quick test with a Matlab code just print whatever I got from 'getenv' and it appeared to be working fine. When J = 1, it printed 1, etc.

However, when I actually run my entire code, it seems to be changing the index value. For example, when J = 1, it calls i = 49 for some reason. And then J = 2, it calls i = 50, etc...

Since I had run a test and it worked fine, I am assuming it is something to do with how I wrote my Matlab code:

close all
clear all
clc

i = getenv('PBS_ARRAY_INDEX');
%% Adding path and loading data

addpath (genpath('/30days/s4364336/CTb3_Turbulence'))
 

    fn = {'t001','t002','t003','t004','t005','t006','t007','t008','t009','t010','t011',...
    't012','t013','t014','t015','t016','t017','t018','t019','t020','t021','t022','t023',...
    't024','t025','t026','t027','t028','t029','t030','t031','t032','t033','t034','t035','t036',...
    't037','t038','t039','t040','t041','t042','t043','t044','t045','t046','t047','t048','t049','t050',...
    't051','t052','t053','t054','t055','t056','t057','t058','t059','t060','t061','t062',...
    't063','t064','t065','t066','t067','t068','t069','t070','t071','t072','t073','t074','t075',...
    't076','t077','t078','t079','t080','t081','t082','t083','t084','t085','t086','t087','t088','t089',...
    't090','t091','t092','t093','t094','t095','t096','t097','t098','t099','t100',...
    't101','t102','t103','t104','t105','t106','t107','t108','t109','t110','t111',...
    't112','t113','t114','t115','t116','t117','t118','t119','t120','t121','t122','t123',...
    't124','t125','t126','t127','t128','t129','t130','t131','t132','t133','t134','t135','t136',...
    't137','t138','t139','t140','t141','t142','t143','t144','t145','t146','t147','t148','t149','t150',...
    't151','t152','t153','t154','t155','t156','t157','t158','t159','t160','t161','t162',...
    't163','t164','t165','t166','t167','t168','t169','t170','t171','t172','t173','t174','t175',...
    't176','t177','t178','t179','t180','t181','t182','t183','t184','t185','t186'};


tic
%% Load data - i is from the loop in the HPC

load(['CTb3_A1_', fn{i},'_ProcessedTurbulence.Struct.mat']);

Does anyone have any idea why this is happening? I tried running the same code, but shortening fn to t001 to t048. That gives me an error because it can't load the data (it looks for t049 straight away when J = 1).

Thanks!

Larissa