我想問下一條通項

(A)
3,9,19,33,51,73,99

(B)
3,10,29,66,127,218,345,514,731,1002,1333,1730,........

2006-11-04 05:01:30 補充：
c) 3,10,21,36,55,78....(n-1)既二次方 (n)x(n-1)(n-1)(n-1)即是1既二次方 2x1 = 32既二次方 3x2 = 103既二次方 4x3 = 214既二次方 5x4 = 365既二次方 6x5 = 55from http://hk.knowledge.yahoo.com/question/?qid=7006092800815

2006-11-04 05:07:42 補充：
d) 4,12,24,40,60, 84, 112, 144, 180 from :

2006-11-04 05:08:27 補充：
Explaination for D.#1 = 4 = 4 #2 = 4 8 = 12 #3 = 4 8 12 = 24 #4 = 4 8 12 16 = 40 #5 = 4 8 12 16 20 = 60 The final # is equal to half the last number being added times (n 1). For example, in #3, half of 12 times 4 = 24. Or in #4, half of 16 times 5 = 40.

(A) 73
3+6=9
9+10=19
19+14=33
33+18=51
51+22=73

The differences will be 6,10,14,18,22,26,30,34...X+4


(B) 218
3+7=10
10+19=29
29+37=66
66+61=127
127+91=218

The differences will be 7,19,37,61,91....(X(n-1)-X(n-2)+6)

(a) general term= 2n^2 + 1 (it is transformed from the sequence of square number)

(b) general term= n^3 + 2(derived from cubic number)

2006-11-02 15:49:38 補充：
Both c and d derived from triangular no.(c) 2n² n(d) 2n² 2n

2006-11-02 15:50:52 補充：
there are problems in display.(c) 2n^2 n(d) 2n^2 2n

2006-11-02 15:52:06 補充：
(c) 2n^2 + n(d) 2n^2 + 2n