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A184880
Diagonal sums of number triangle A184879.
1
1, 1, 2, -1, 1, 4, 21, 33, 30, 19, 33, 240, 537, 961, 922, 1223, 2753, 8380, 17725, 27873, 37494, 57627, 132577, 300648, 589953, 942465, 1460146, 2566159, 5351297, 11014388, 20304613, 34080673, 57005646, 105116835, 207381921, 402618208, 728728425, 1262355777, 2218248522, 4121995735, 7892039233
OFFSET
0,3
FORMULA
G.f.: ( 1-x-x^2 ) / ( (4*x^3+3*x^2-x-1)*(4*x^3-5*x^2+3*x-1) )
a(n) = 2*a(n-1)+a(n-2)- 6*a(n-3)+7*a(n-4)+8*a(n-5)-16*a(n-6). [Harvey P. Dale, Sep 11 2011]
MATHEMATICA
CoefficientList[Series[(1-x-x^2)/(1-2x-x^2+6x^3-7x^4-8x^5+16x^6), {x, 0, 50}], x] (* or *) LinearRecurrence[{2, 1, -6, 7, 8, -16}, {1, 1, 2, -1, 1, 4}, 50] (* Harvey P. Dale, Sep 11 2011 *)
CROSSREFS
Cf. A184879.
Sequence in context: A075803 A127966 A326570 * A257859 A231622 A165623
KEYWORD
sign,easy
AUTHOR
Paul Barry, Jan 24 2011
STATUS
approved