c – Como dividir um vetor em semanas?

/Eu recebi o código de um vetor com dados de 181 dias. Preciso calcular a média semanal desses dados. Mas não tenho muita ideia de como dividir todo o vetor em semanas. Sou iniciante em C e não tenho muita noção, alguma maneira boa de fazer isso?/

insira o código // Numero de dias registrados

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>

#define NDIAS 181
// Quantidade diaria de novos casos
int main(void){
int bra_nvcasos(NDIAS)={24605,15827,17341,20006,56648,63430,87843,52035,62290,29792,25822,64025,60899,67758,69198,61567,33040,23671,62094,64385,59119,56552,62334,28323,26816,61963,63520,61811,59826,58462,27756,24591,54096,56002,56873,50872,0,77475,0,74925,59602,54742,51546,44299,24759,32197,55271,56766,51879,53582,54940,29026,26986,62715,66588,65998,65169,61602,34027,35742,59925,71704,75102,75495,69609,80508,32321,70764,79876,75412,85663,76178,43812,36239,83926,90303,86982,90570,79069,47774,49293,82493,89992,100158,84245,85948,44326,38927,84494,90638,91097,70238,43515,31359,28645,86979,92625,86652,93317,71832,37017,35785,82186,73513,73174,85774,67636,42980,30624,69381,79719,45178,69105,71137,32572,28636,72140,79726,69389,68333,66964,28935,24619,77359,73295,73380,78886,63430,38911,25200,72715,76692,74592,85536,67009,40709,30148,75445,79219,82039,76855,76490,35819,37498,73453,80486,67467,49768,79670,43520,30434,78926,95601,83391,37936,66017,39637,37156,52911,85748,88092,85149,78700,37948,39846,80609,95367,74042,98832,82288,44178,38903,87822,115228,73602,79277,64134,33704,27804,64903,43836};
int sem;