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A212240 Number of 2 X 2 matrices M of with all terms in {1,...,n} and permanent(M) >= n. 2
0, 1, 16, 80, 251, 612, 1269, 2354, 4021, 6449, 9844, 14427, 20458, 28203, 37972, 50073, 64876, 82725, 104046, 129222, 158741, 193024, 232607, 277956, 329675, 388248, 454353, 528508, 611435, 703712, 806121, 919242, 1043953, 1180865 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
For a guide to related sequences, see A211795.
LINKS
FORMULA
a(n) + A212151(n) = n^4.
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x + y*z >= n, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]] (* A212240 *)
(* Peter J. C. Moses, Apr 13 2012 *)
CROSSREFS
Sequence in context: A008511 A130810 A212090 * A050468 A242167 A068778
KEYWORD
nonn
AUTHOR
Clark Kimberling, May 07 2012
EXTENSIONS
Offset changed to 0 by Georg Fischer, Feb 03 2022
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)