Verified answer

a1=1

a7= a1+6d=25

d=4

a2= a1+d= 1+4= 5

a3= a1+ 2d= 1+8= 9

a4= a1+3d= 1+ 12= 13

a5= a1+4d= 1+ 16= 17

a6= a1+ 5d= 1+20= 21

1, 5, 9, 13, 17, 21, 25