得:q=
3p+1 |
2 |
2p+2+p?1 |
2 |
p?1 |
2 |
要使q為正整數(shù),則只要p為正奇數(shù),
∵a1=3×1+5=8,
a2n+1-a2n-1=3(2n+1)+5-3(2n-1)-5=6.
∴數(shù)列{a2n-1}是以8為首項(xiàng),6為公差的等差數(shù)列,
取出數(shù)列{an}的奇數(shù)項(xiàng),按原順序排列,即構(gòu)成數(shù)列{cn},
∴cn=8+6(n-1)=6n+2.
故答案為:cn=6n+2.
3p+1 |
2 |
2p+2+p?1 |
2 |
p?1 |
2 |