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<DIV>Neil, </DIV>
<DIV>
<DIV> The sequences: A045501, A045499, A045500,<BR>return:
"Unexpected error."<BR> <BR>Perhaps you are aware of this?</DIV>
<DIV> </DIV></DIV>
<DIV>> there was a discussion here in November about this.<BR>> based on
emails from Emeric, Paul H. and especially Richard Mathar, <BR>> I'm<BR>>
adding the missing entry as A121207.<BR>> Neil<BR> <BR>Also,
following is an observation regarding A121207 worth
sharing. <BR> <BR>Consider the row reversal of triangle
A121207;</DIV>
<DIV>of course, the resultant triangle equals Emeric's triangle A124496
<BR>with an additional left column (=A000110 Bell numbers). <BR> <BR>What
is interesting is the simplicity of the matrix inverse.<BR> <BR>The matrix
inverse of the row-reversal of A121207 begins: <BR>1;<BR>-1, 1;<BR>-1, -1,
1;<BR>-1, -2, -1, 1;<BR>-1, -3, -3, -1, 1;<BR>-1, -4, -6, -4, -1, 1;<BR>-1, -5,
-10, -10, -5, -1, 1;<BR>-1, -6, -15, -20, -15, -6, -1, 1;<BR>-1, -7, -21, -35,
-35, -21, -7, -1, 1;<BR>-1, -8, -28, -56, -70, -56, -28, -8, -1, 1;
...<BR> <BR>This gives the recurrence and the reason that the Bell numbers
appear. </DIV>
<DIV> Paul</DIV></BODY></HTML>