Mathematica program generating sequence of points stalls for no apparent reason.

*To*: mathgroup at smc.vnet.net*Subject*: [mg58009] Mathematica program generating sequence of points stalls for no apparent reason.*From*: "Gilmar" <gilmar.rodriguez at nwfwmd.state.fl.us>*Date*: Thu, 16 Jun 2005 05:36:23 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

The following program is a slight variation of a program found in: http://www.research.att.com/cgi-http://www.research.att.com/cgi-bin /access.cgi/as/njas/sequences/eisA.cgi?Anum=A065978 f[n_] := For[p=n/2,True,p--,If[PrimeQ[p]&&PrimeQ[n-p],Return[(n/2)-p]]]; For[n=4; max=-1, True,n+=2,If[f[n]>max,Print[{n,f[n]}]; max=f[n]]] After generating the points: {{4,0},{8,1},{16,3},{44,9},{92,15},{242,18},{256,21},{272,27},{292,33}, {476,39},{530,42},{572,45},{682,48},{688,75},{1052,87},{1808,93}, {2228,117},{3382,120},{3472,135},{3502,138},{3562,168},{4952,183}, {6194,210},{7102,228},{10262,300},{17008,333},{20684,369},{37052,393}, {45128,453},{49552,525},{80144,621},{137414,720},{251806,810}, {349826,846},{362534,1086},{742856,1281},{1655152,1305},{1872236,1515}, {2108282,1590},{2319728,1617},{2707118,1722},{5182214,1794}, {7518328,1833},{10908124,1851},{11939162,2010},{12727966,2064}, {13279472,2085},{13583338,2112},{14366372,2217},{18245438,2352}, {21572990,2754}} I'm attempting to obtain points higher than {21572990,2754} via: f[n_] := For[p=n/2,True,p--,If[PrimeQ[p]&&PrimeQ[n-p],Return[(n/2)-p]]]; For[n=115978712; max=-1, True, n+=2, If[f[n]>max, Print[{n, f[n]}]; max=f[n]]] I'm running the program for a period of (say) one day, but the program lingers at the 9928 K's level of PC memory, without producing any other points. I know that my PC is not running out of memory, because (if this was the case then) Mathematica would give the message: "No more memory available. Mathematica kernel has shut down. Try quitting other applications and then retry." My question is: Why is this happening? Thank you for your help!