SOLUTION: What is the next number in the series: 9,73,241,561,1081,1849,...

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Question 736986: What is the next number in the series: 9,73,241,561,1081,1849,...
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
general formula is:
a%5Bn%5D=8n%5E3%2B4n%5E2-4n%2B1
check if it works with first two terms:
a%5B1%5D=8%2A1%5E3%2B4%2A1%5E2-4%2A1%2B1
a%5B1%5D=8%2B4-4%2B1
a%5B1%5D=13-4
a%5B1%5D=9
a%5B2%5D=8%2A2%5E3%2B4%2A2%5E2-4%2A2%2B1
a%5B1%5D=8%2A8%2B4%2A4-4%2A2%2B1
a%5B2%5D=64%2B16-8%2B1
a%5B2%5D=81-8
a%5B2%5D=73
so, next term in a%5B1%5D=9,a%5B2%5D=73, a%5B3%5D=241,a%5B4%5D=561,a%5B5%5D=1081, a%5B6%5D=1849, that we are looking for is a%5B7%5D

a%5B7%5D=8%2A7%5E3%2B4%2A7%5E2-4%2A7%2B1
a%5B7%5D=2744%2B196-28%2B1
a%5B7%5D=2913