1,6,11,16,21,26,31,36,41,46
1+6+11+16+21+26+31+36+41+46=235
a1=1,a2=6,a3=11,
a2-a1=a3-a2=
a2-a1=d, d=6-1, d=5
a10=a1+9d, a10= 1+45=46
s10=10(1+46)/2=5.47=235
Otvet: 235
(sn=n(a1+an)/2)
