What are the next few numbers in the sequence? 1, 6, 18, 40, 75, 126, ...?

The terms of the given sequence corresponds to the positive (non-zero) Pentagonal Pyramidal Numbers which possess the form n^2*(n+1)/2

Hence, the nth term of the sequence s(n) = n^2*(n+1)/2

Accordingly, s(7) = 196; s(8) = 288 ; s(10) = 405; s(11) = 550;
s(12) = 726.

Consequently, the next few terms of the sequence are 196, 288, 405, 550, 726, ......

Edited on April 9, 2007, 3:01 pm

Posted by K Sengupta on 2007-04-09 15:01:14