Posted by **deli** on Monday, April 29, 2013 at 11:27am.

Consider all 3-term geometric sequences with first term 1 and with common ratio the square of an integer between 1 and 1000. How many of these 1000 geometric sequences have the property that the sum of the 3 terms is prime?

- algebra -
**Reiny**, Monday, April 29, 2013 at 12:58pm
I did this question here

http://www.jiskha.com/display.cgi?id=1367223190

Somebody called "tsong" disagreed, but clearly did not read my solution, since I "proved" that there is only one such case,

when the GS is 1 , 1, 1

that is, when the common ratio is 1

then 1 + 1^2 + 1^4 = 3 , which is a prime number

conclusion: there is only ONE such sequence.

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