Mathematical Puzzle

[pirwany]

PLEASE help me with this puzzle:

What is the value of 51 if:
1=1
2=2
3=4
4=7
5=12
10=143

Thank you.

[factor-fiction]

53,316,291,172

[factor-fiction]

the first 20 terms are:
1 = 1
2 = 2
3 = 4
4 = 7
5 = 12
6 = 20
7 = 33
8 = 54
9 = 88
10 = 143
11 = 232
12 = 376
13 = 609
14 = 986
15 = 1,596
16 = 2,583
17 = 4,180
18 = 6,764
19 = 10,945
20 = 17,710

[factor-fiction]

Next 31 terms:
21 = 28,656
22 = 46,367
23 = 75,024
24 = 121,392
25 = 196,417
26 = 317,810
27 = 514,228
28 = 832,039
29 = 1,346,268
30 = 2,178,308
31 = 3,524,577
32 = 5,702,886
33 = 9,227,464
34 = 14,930,351
35 = 24,157,816
36 = 39,088,168
37 = 63,245,985
38 = 102,334,154
39 = 165,580,140
40 = 267,914,295
41 = 433,494,436
42 = 701,408,732
43 = 1,134,903,169
44 = 1,836,311,902
45 = 2,971,215,072
46 = 4,807,526,975
47 = 7,778,742,048
48 = 12,586,269,024
49 = 20,365,011,073
50 = 32,951,280,098
51 = 53,316,291,172
Can you see the pattern?

[Fibonacci]

Yes I can !

[factor-fiction]

Well of course you would, with a user name of Fibonacci. You probably discovered this sequence too.