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A212889
Number of (w,x,y,z) with all terms in {0,...,n} and even range.
3
1, 2, 53, 104, 349, 594, 1273, 1952, 3401, 4850, 7501, 10152, 14533, 18914, 25649, 32384, 42193, 52002, 65701, 79400, 97901, 116402, 140713, 165024, 196249, 227474, 266813, 306152, 354901, 403650, 463201, 522752, 594593, 666434
OFFSET
0,2
COMMENTS
a(n)+A212890(n)=(n+1)^4. For a guide to related sequences, see A211795.
FORMULA
a(n)=2a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-5)-2*a(n-6)-2*a(n-7)+a(n-8).
G.f.: f(x)/g(x), where f(x)=-1-47*x^2-47*x^4-x^6 and g(x)=((-1+x)^5)*(1+x)^3.
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0}, (Do[If[(Mod[#, 2] == 0) &[Max[w, x, y, z] - Min[w, x, y, z]], s++], {w, 0, n}, {x, 0, n}, {y, 0, n}, {z, 0, n}]; s)]];
Map[t[#] &, Range[0, 40]] (* A212889 *)
CROSSREFS
Sequence in context: A167771 A062853 A059703 * A041337 A139844 A249657
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 30 2012
STATUS
approved