First term of each sets are 1,2,4,7,... Let S=1+2+4+7+...+Tn S=1+2+4+...+Tn On subtracting, we get 0=1+1+2+3+...−Tn Tn=1+(1+2+3+...(n−1) terms ) Tn=1+
(n−1)n
2
T50=1+
49×50
2
∴T50=1226 ⇒ First term of 50 th set is 1226 , therefore series is 1226,1227,...50 terms S=
