That sounds reasonable, except, following the pattern you suggest, 77 would not be followed by 90 but by 100 instead. Following the rest of the steps you did, the answer for the next letter in the sequence is 'v', not 'L'
blackjack
<a href="http://c.casalemedia.com/c?s=51816&f=3&id=0" target="_blank"><img src="http://as.casalemedia.com/s?s=51816&u=http://perplexus.info&f=3&id=0&if=0" width="120" height="600" border="0"></a>
flooble's webmaster puzzle
re: Looks like a lot of letters to me
