<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV><DIV>zak seidov:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Monaco" size="5" style="font: 16.0px Monaco">Hope someone may wish to add more terms:</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Monaco" size="5" style="font: 16.0px Monaco">Mathematica isn't the best in such calcs.</FONT></P></BLOCKQUOTE><BR><BLOCKQUOTE type="cite"> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Monaco" size="5" style="font: 16.0px Monaco">%S A124450</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Monaco" size="5" style="font: 16.0px Monaco">5,47,491,4919,49877,499943,4999913,49999757,499999931,4999999937,49999999811,499999999769,4999999998431,49999999999619,499999999999769,4999999999998557,49999999999998887,499999999999999679,4999999999999999661,49999999999999998647</FONT></P> <P style="margin: 0.0px 0.0px 0.0px 0.0px"><FONT face="Monaco" size="5" style="font: 16.0px Monaco">%N A124450 Lesser of pair of closest primes summed to 10^n.</FONT></P></BLOCKQUOTE><BR></DIV><DIV>I think you overstate the Mathematica difficulty. With no effort at any sort of efficiency in the programming, it still only takes me 8 seconds to generate 50 terms.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Table[h =10^n/2; c=0; While[PrimeQ[h-c]==False || PrimeQ[h+c]==False, c++]; h-c, {n, 1, 50}]</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>{5, 47, 491, 4919, 49877, 499943, 4999913, 49999757, 499999931, 4999999937, 49999999811, 499999999769, 4999999998431, 49999999999619, 499999999999769, 4999999999998557, 49999999999998887, 499999999999999679, 4999999999999999661, 49999999999999998647, 499999999999999999637, 4999999999999999999481, 49999999999999999998677, 499999999999999999998497, 4999999999999999999999259, 49999999999999999999998779, 499999999999999999999999043, 4999999999999999999999998947, 49999999999999999999999999661, 499999999999999999999999994069, 4999999999999999999999999997879, 49999999999999999999999999997699, 499999999999999999999999999997969, 4999999999999999999999999999995227, 49999999999999999999999999999995263, 499999999999999999999999999999989719, 4999999999999999999999999999999998683, 49999999999999999999999999999999999871, 499999999999999999999999999999999996127, 4999999999999999999999999999999999998557, 49999999999999999999999999999999999999613, 499999999999999999999999999999999999988231, 4999999999999999999999999999999999999991729, 49999999999999999999999999999999999999994663, 499999999999999999999999999999999999999997117, 4999999999999999999999999999999999999999992863, 49999999999999999999999999999999999999999991807, 499999999999999999999999999999999999999999991507, 4999999999999999999999999999999999999999999993199, 49999999999999999999999999999999999999999999997081}</DIV><DIV><BR class="khtml-block-placeholder"></DIV></BODY></HTML>