1 
P1  Recursive Sequence 
SPOJ 

2 
P2  Recursive Sequence (Version II) 
SPOJ 

3 
P3  Fibonacci Sum 
SPOJ 

4 
P4  Sum of Tetranacci numbers (easy) 
SPOJ 

5 
P5  Number of quite different words 
SPOJ 

6 
P6  Tetrahedron 
Codeforces 
Codeforces Round #113 (Div. 2) 
7 
P7  A and B and Lecture Rooms 
Codeforces 
Codeforces Round #294 (Div. 2) 
8 
P8  Fools and Roads 
Codeforces 
Codeforces Round #121 (Div. 1) & Codeforces Round #121 (Div. 2) 