A212751 - OEIS

A212751

Number of (w,x,y,z) with all terms in {0,...,n} and at least one of these conditions holds: w=R, x=R, y=R, z<R, where R = max{w,x,y,z} - min{w,x,y,z}.

1, 14, 70, 198, 477, 924, 1696, 2768, 4405, 6510, 9486, 13134, 18025, 23828, 31312, 39984, 50841, 63198, 78310, 95270, 115621, 138204, 164880, 194208, 228397, 265694, 308686, 355278, 408465, 465780, 530656, 600224, 678385, 761838

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OFFSET

0,2

COMMENTS

For a guide to related sequences, see A211795.

LINKS

Table of n, a(n) for n=0..33.

Index entries for linear recurrences with constant coefficients, signature (2,2,-6,0,6,-2,-2,1)

FORMULA

a(n)=2*a(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.: ( -1-12*x-40*x^2-36*x^3-25*x^4+12*x^5 ) / ( (1+x)^3*(x-1)^5 ).

MATHEMATICA