Kshiteej, Its more than 24 hours and so please update the question and tell us who is the winner.

Ans is 6121.
31-1 = 30 = (3)^3 +3
253-31 = 222 = (6)^3 + 6
991 -253 = 738 = (9)^3 + 9
2731 - 991 =1740 =(12)^3 + 12
so te ans will be 2731 + (15)^3 + 15 =6121

So Congrats xpi0t0s

very nice one kshiteej...

Thanks Mayjune and congrats xpi0t0s.

By the way what was your logic while calculating 6121? The same as of mine??

nice question kshiteej

Congrs xpi0t0s

Heh, no, I did it in a spreadsheet and made a BIG assumption...column A contained the original sequence in A1-A5; B2=A2-A1 and copied the formula to B3-B5, C3-C5, D4-D5 and E5. I assumed that was the end of it and that the next row, if it existed, would end with E6=E5 and worked backwards to find out what would be in D6, C6, B6 and A6, and that's where I got 6121 from.

Then I looked up the sequence in the sequences database as explained (and linked) earlier in the thread.