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Try this TOMATO problem from I.S.I. B.Stat Entrance Objective Problem based on Combination of Sequence.

## Logic and combination of sequence (B.Stat Objective)

The two sequence of numbers {1,4,16,64,…..} and {3,12,48,192,…..} are mixed as follows {1,3,4,12,16,48,64,192,….}. One of the numbers in the mixed series is 1048576. Then the number immediately preceeding it is

• 262144
• 786432
• 814572
• 786516

### Key Concepts

Logic

Sequence

Integers

But try the problem first…

Source

B.Stat Objective Question 79

Challenges and Thrills of Pre-College Mathematics by University Press

## Try with Hints

First hint

The first series is of form $4^{r}$ for $r \geq 0$ $r \in$ set of natural numbers the second series is of form $3 \times 4^{r}$ for $r \geq 0$ $r \in$ set of natural numbers and the third series is of $4^{r}$,$3 \times 4^{r}$ in alternate element form for $r \geq 0$ $r \in$ set of natural numbers

Second Hint

given that 1048576=$4^{r}$=$4^{10}$

Final Step

then preceeding term $3 \times 4^{9}$=(3)(262144)=786432.