By a quick Google search I've found a probable solution: Let a[0]=408;a[1]=571;a[2]=332;a[3]=377 and for n>3 let a[n]=round(sqrt(n-2)*a[n-4]) So this isn't a hard sequence. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://list.seqfan.eu/pipermail/seqfan/attachments/20070626/04891731/attachment-0001.htm>